Abstract:
Apparatus and methods are provided for regulating the power consumption within a wireless communications mobile handset. A base station transmits an RF power output designating signal that indicates a desired level of the RF power output from the mobile handset. The mobile handset receives the RF power output designating signal, where it is used to set the level of the DC power supplied to the mobile handset. In this manner, the minimum amount of power necessary to maintain linear operation of the mobile handset is expended in the mobile handset. The DC power level is set by internally generating a control signal. The level of the control signal is dictated by the desired level of the RF power output as indicated by the received RF power output designating signal. The control signal is then applied to an RF amplifier circuit contained within the mobile handset to set the DC power level. The DC power level can be further varied from the set DC power level in proportion to an envelope of an RF input signal to provide a more power-efficient mobile handset.

Description:
RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 09/080,773, filed on May 18, 1998, now U.S. Pat. No. 6,008,698. 
    
    
     FIELD OF THE INVENTION 
     The present inventions are directed to methods and apparatus for operating a mobile unit more efficiently and linearly over a range of given RF signal output power levels. 
     In accordance with an aspect of the present inventions, the DC power consumed by a wireless communications mobile handset is regulated by transmitting an RF power output designating signal from a base station, wherein the RF power output designating signal indicates a desired power level of an RF signal output from the mobile handset. The RF power output designating signal is then received by the mobile handset, where it is used to set the level of the DC power provided to the mobile handset. Preferably, the level of the DC power is set to the minimum value necessary to maintain linear operation of an RF amplifier circuit contained within the mobile handset. The level of the DC power can be set by generating a control signal within the mobile handset. The level of the control signal is selected based on the RF power output designating signal. By way of non-limiting example, the control signal level can be selected from a plurality of control signal levels, wherein the control signals correspond to a respective plurality of RF power output levels. Thus, the control signal level corresponding to the RF power output level designated by the RF power output designating signal will be selected. 
     In accordance with a further aspect of the present invention, the DC power level is varied from the set DC power level in proportion to an envelope of the RF output signal. This can be accomplished by sensing the envelope of the RF output signal to produce a sampled envelope signal, which can then be added to the control signal. 
     In accordance with still a further aspect of the present inventions, a feedback loop, in conjunction with the control signal, can be used to set the level of the DC power. By way of non-limiting example, a supply current tracking signal, which indicates the present level of current supplied to an RF amplifier circuit contained in the mobile handset, is generated. The difference between the control signal and the supply current tracking signal is determined to obtain a biasing signal. The supply current, and thus the DC power supplied to the RF amplifier circuit, is then varied in proportion to the biasing signal. Alternatively, a supply voltage tracking signal, which indicates the present level of voltage supplied to the RF amplifier circuit, is generated. The difference between the control signal and the supply voltage tracking signal is determined to obtain the biasing signal. The supply voltage, and thus the DC power supplied to the RF amplifier circuit, is then varied in proportion to the biasing signal. 
     In accordance with still a further aspect of the present inventions, the RF power output designating signal indicates the existence of either a high RF output power condition or a low RF output power condition. The RF input signal is amplified through a driver. During a high RF output power condition, the DC power is provided to the RF amplifier circuit, and the RF signal is further amplified through the RF amplifier circuit. During a low RF output power condition, the flow of DC power to the RF amplifier circuit is impeded, and further amplification of the RF input signal is bypassed. 
     To further enhance the linearity and efficiency of the RF amplifier circuit, various features of the above-mentioned embodiments can be combined. 
     The present invention pertains to power amplifiers, including more specifically, a power amplifier circuit for wireless communication systems. 
     BACKGROUND OF THE INVENTION 
     In wireless communication systems, mobile handsets communicate with other mobile handsets through base stations connected to the PSTN (public switched telephone network). Typically, in FDMA systems the base stations determine the frequencies at which the handsets are to communicate and send signals to the handsets to adjust the transmission power of the handsets. 
     The signals that are transmitted by the handsets are typically amplified prior to transmission to the base station. The amplification of the signal within the handset is generally performed by a radio frequency (RF) power amplifier  10 , a representative embodiment of which is depicted in FIG. 1 (PRIOR ART). The RF power amplifier  10  includes a DC power terminal  12  and ground terminal  14 . A DC power source  16  is typically connected between the power terminal  12  and the ground terminal  14 , producing a supply voltage, V S , at the power terminal  12  and a supply current, I S , into the power terminal  12 . Thus, the RF power amplifier is supplied with a DC power, P DC , equal to V S *I S . An RF input signal, RF in , generated by the transmitting handset, is fed into the RF power amplifier  10  via an RF input terminal  18 . The RF power amplifier  10  amplifies the RF input signal, RF in , to produce an RF output signal, RF out , at an RF output terminal  20 . The RF output signal, RF out , after passing through signal processing circuits, is typically sent to the antenna for transmission. An RF input signal, RF in , has an average input signal power, P in , and an RF output signal, RF out , has an average output signal power, P out . 
     When transmitting a signal with a non-constant envelope from a handset it is desirable to operate the power amplifier  10  in a linear mode to minimize signal distortion and bandwidth required to transmit the signal. The linearity of the power amplifier, which is measured by the uniformity of the transfer characteristic (P out /P in ), varies with I S , V S , and RF out . Referring to FIG. 2 (PRIOR ART), the curves C 1 , C 2 , and C 3  represent compression characteristics of an RF power amplifier  10  of FIG. 1, given three exemplary amplifier DC power, P DC , levels. The line L represents linear operation of the amplifier  10 . As curves C 1 , C 2 , and C 3  illustrate, the linearity of the power amplifier depends on P DC . That is, as P DC , increases, the range of P in  values for which the amplifier remains linear increases. In general, the output power, P out , for which a power amplifier compresses increases with the DC power supplied to the power amplifier. 
     Although supplying a relatively high DC power to the RF power amplifier  10  will generally maintain linear operation of the RF power amplifier  10 , such an arrangement becomes less advantageous in a system with varying transmission power requirements. A wireless communications system restricts the transmission power of the handset to minimize the signal from propagating to an excessively far point, so that the same frequency may be used at a far point, i.e., in other cells in order to permit servicing of as many subscribers as possible within the finite frequency resources allocated to the system. At the same time, the transmission power must be high enough to maintain the integrity of the transmitted signal over the distance that it travels to a base station. The magnitude of the handset transmission power required to maintain proper communication with a base station is dictated in part by the distance and the electrical communication environment between the handset and the base station. That is, if the handset is located far from a base station, the level of the RF output signal power, P out , will be relatively high. If the handset is located close to the base station, the level of the RF output signal power, P out , will be relatively low. 
     In a situation requiring a relatively low handset transmission power, an RF power amplifier that is supplied with a high DC power is inefficient. Referring to FIG. 1, the power the power amplifier  10  dissipates as heat is equal to the difference between the power supplied to the RF amplifier  10 , P DC  and P in , and the RF output signal power, P out , as characterized by the equation, P HEAT =P DC +P in −P out . Thus, given a constant DC supply power, P DC , the lower the RF output signal power, P out , is, the more power the amplifier wastes as heat. The wasted power in the power amplifier  10  can be quantified in the power efficiency equation, P eff =P out /(P DC +P in ). Thus, the more DC power that is supplied to an RF power amplifier, the less efficient that RF power amplifier becomes for a constant P in  and P out . 
     Therefore, it can be understood that an RF power amplifier that is supplied with a relatively high constant DC power generally operates linearly over a full range of RF output signal, power levels, but is power inefficient, thus leading to significantly increased battery and heat sinking requirements, heavier battery weight, and shorter battery life. On the other hand, a power amplifier that is supplied with a relatively low constant DC power is power efficient, but generally operates only linearly over a low range of RF output signal power levels, thus resulting in a distorted transmission signal with a larger bandwidth. 
     There thus remains a need to operate a power amplifier more efficiently and linearly over a full range of given RF signal output power levels. 
     SUMMARY OF THE INVENTION 
     The present inventions solve this problem. The adaptable DC power consumption amplifier circuit of the present inventions include a control circuit such that an RF amplifier operates more efficiently and linearly over a full range of given RF signal output power levels. 
     In a preferred embodiment of the present inventions, there is provided an adaptable supply current circuit that maintains the supply current in an RF amplifier at a desired level. A supply current tracking signal indicative of the present level of the supply current, and a control signal indicative of the desired level of the supply current are generated. A biasing signal is generated based upon the difference between the control signal and the supply current tracking signal. The biasing signal is applied to the RF amplifier. 
     In another preferred embodiment of the present inventions, there is provided a dynamically adaptable supply current circuit that dynamically varies the supply current in RF amplifier from a desired level. A supply current tracking signal indicative of the present level of the supply current, and a control and envelope tracking signal indicative of the desired level of the supply current and the present level of a modulated RF output signal are generated. A dynamic biasing signal is generated based upon the difference between the control and envelope tracking signal and the supply current tracking signal. The dynamic biasing signal is applied to the RF amplifier. 
     To further enhance the linearity and efficiency of an RF amplifier, various features of the above-mentioned embodiments can be combined with features of other circuits disclosed in this specification, such as, e.g., an adaptable supply voltage circuit, a dynamically adaptable supply voltage circuit, or a bypassable circuit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a prior art circuit diagram of a conventional RF amplifier; 
     FIG. 2 is a graph showing exemplary compression characteristics of the prior art conventional RF amplifier of FIG. 1; 
     FIG. 3 is a block diagram of a prior art conventional RF amplifier depicting a modulated RF input signal amplified to create a modulated RF output signal; 
     FIG. 4 is a block diagram of an adaptable supply current circuit in use with a single-stage RF amplifier; 
     FIG. 5 is a block diagram of an alternative adaptable supply current circuit in use with a single-stage RF amplifier; 
     FIG. 6 is a block diagram of an adaptable supply current circuit in use with an N-stage RF amplifier; 
     FIG. 7 is a circuit diagram of the adaptable supply current circuit of FIG. 6; 
     FIG. 8 is a circuit diagram of a two-stage RF power amplifier for use in the adaptable supply current circuit of FIG. 7; 
     FIG. 9 is a circuit diagram of a three-stage RF power amplifier for use in the adaptable supply current circuit of FIG. 7; 
     FIG. 10 is a graph showing exemplary compression characteristics of the RF amplifier employed in the adaptable supply current circuit of FIG. 7; 
     FIG. 11 is a block diagram of a dynamically adaptable supply current circuit; 
     FIG. 12 is a block diagram of an alternative embodiment of a dynamically adaptable supply current circuit; 
     FIG. 13 is a circuit diagram of the dynamically adaptable supply current circuit of FIG. 11; 
     FIG. 14 is a circuit diagram of the preferred dynamically adaptable supply current circuit of FIG. 11; 
     FIG. 15 is a block diagram of an adaptable supply voltage circuit; 
     FIG. 16 is a block diagram of an alternative embodiment of an adaptable supply voltage circuit; 
     FIG. 17 is a circuit diagram of the adaptable supply voltage circuit of FIG. 15; 
     FIG. 18 is a block diagram of a dynamically adaptable supply current and voltage circuit; 
     FIG. 19 is a block diagram of a bypassable circuit; 
     FIG. 20 is a block diagram of an alternative embodiment of a bypassable circuit; 
     FIG. 21 is a block diagram of a bypassable dynamically adaptable supply current circuit; 
     FIG. 22 is a block diagram of a bypassable dynamically adaptable supply voltage circuit; 
     FIG. 23 is a block diagram of a bypassable dynamically adaptable supply current and voltage circuit; 
     FIG. 24 is a block diagram of an alternative embodiment of a bypassable circuit. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 4 depicts an adaptable supply current circuit  50 , which can be employed to operate an RF amplifier  52  contained in the adaptable supply current circuit  50  more efficiently and linearly by controlling a supply current, I S , within the RF amplifier  52 . The RF amplifier  52  is a single-stage amplifier, which can be used as one stage of a multi-stage amplifier. The adaptable supply current circuit  50  includes a power supply  54  having an output terminal  55 . An RF input signal, RF in , is fed into an RF input terminal  70  of the RF amplifier  52 . An amplified RF output signal, RF out , is output on an RF output terminal  72  of the RF amplifier  52 . 
     The supply current, I S , is controlled through a feedback control loop  78  comprising a current detector  58 , a controller  60 , and a signal processor  80 . The power supply  54  supplies current, I S , to the RF amplifier  52  through the current detector  58 . The current detector  58  includes an input terminal  82  connected to the output terminal  55  of the power supply  54 , and an output terminal  83  connected to the power terminal  68  of the RF amplifier  52 . The current detector  58  further includes a coupling terminal  84  connected to a first input terminal  85  of the signal processor  80 . The current detector  58  samples a current on the input terminal  82  of the current detector  58  and supplies the supply current, I S , on the output terminal  83  of the current detector  58 . The current detector  58  produces a sampled supply current signal, S IS , on the coupling terminal  84  of the current detector  58 , influencing a supply current tracking signal, S TRK-IS , on the first input terminal  85  of the signal processor. The supply current tracking signal, S TRK-IS , indicates the present level of the supply current, I S . As shown in phantom, the current detector  58  can alternatively sample a supply current, I S ′, equal to the sum of the supply current, I S , and the RF amplifier gate current (not shown), on a ground terminal  76  of the RF amplifier  52 . An example of a device that can be used as the current detector  58  is a current mirror. 
     Alternatively, as shown in FIG. 5, the feedback control loop  78  includes a current detector  53  with an input terminal  57  connected to the power terminal  68  of the RF amplifier  52 , and an output terminal  59  connected to the first input terminal  85  of the signal processor  80 . The current detector  53  samples the supply current, I S , on the power terminal  68  of the RF amplifier  52  and produces the sampled supply current signal, S IS , on the output terminal  59  of the current detector  53 , influencing the supply current tracking signal, S TRK-IS , on the first input terminal  85  of the signal processor. As shown in phantom, the current detector  53  can alternatively sample the supply current, I S ′, on the ground terminal  76  of the RF amplifier  52 . An example of a device that can be used as the current detector  53  is a resistor. 
     The controller  60  includes an input terminal  63  into which an RF power designating signal, S RFOUT , designating a desired average RF output signal power, P out , and thus, the desired supply current, I S , is input. The controller  60  further includes an output terminal  61  that is connected to a second input terminal  86  of the signal processor  80 . The controller  60  produces a control signal, S C , on the output terminal  61  of the controller  60  in accordance with the RF power designating signal, S RFOUT , influencing a control tracking signal, S TRK-C , on the second input terminal  86  of the signal processor  80 . The control tracking signal, S TRK-C , indicates the desired average level of the supply current, I S . 
     The signal processor  80  includes a subtractor  62 , an amplifier  64 , and an integrator  66 . The subtractor  62  determines the difference between the control tracking signal, S TRK-C , and the supply current tracking signal, S TRK-IS . The amplifier  64  is preferably employed to scale the difference between the control tracking signal, S TRK-C , and the supply current tracking signal, S TRK-IS . The gain of the amplifier  64  can be greater or less than unity. The integrator  66  is preferably employed to integrate the difference between the control tracking signal, S TRK-C , and the supply current tracking signal, S TRK-IS . The signal processor  80  produces a gate biasing signal, S G , on an output terminal  87  of the signal processor  80 . The output terminal  87  of the signal processor  80  is connected to a control terminal  74  of the RF amplifier  52 . The gate biasing signal, S G , is fed into the control terminal  74  of the RF amplifier  52 . The control terminal  74  of the RF amplifier  52  is coupled with the gate of the RF amplifier  52 . The scaling and integration steps are not limited to the particular order described above, and can be performed in any order or simultaneously to obtain the gate biasing signal, S G . 
     FIG. 6 shows an adaptable supply current circuit  100  with an N-stage RF amplifier  102  having an N number of gain stages (shown in phantom) connected in series. The adaptable supply current circuit  100  is similar to the adaptable supply current circuit  50  shown in FIG. 3, and to the extent the components of each are the same, the same reference numerals have been used. 
     The Nth−1 gain stage and the Nth, gain stage are respectively referred to hereinafter as a preceding gain stage  104  and a final gain stage  106 . The RF input signal, RF in , is fed into an RF input terminal  120  of the RF amplifier  102 . An amplified RF output signal, RF out , is output on an RF output terminal  122  of the RF amplifier  102 . 
     The power supply  54  supplies a current, I SP , to the preceding gain stage  104  through the current detector  58 . The input terminal  82  of the current detector  58  is connected to the output terminal  55  of the power supply  54 , and the output terminal  83  of the current detector  58  is connected to the power terminal  108  of the preceding gain stage  104 . The current detector  58  samples a current on the input terminal  82  of the current detector  58  and supplies the supply current, I SP , on the output terminal  83  of the current detector  58 . The current detector  58  produces a sampled supply current signal, S ISP , on the coupling terminal  84  of the current detector  58 , influencing a supply current tracking signal, S TRK-ISP , on the first input terminal  85  of the signal processor. The supply current tracking signal, S TRK-ISP , indicates the present level of the supply current, I SP . The output terminal  55  of the power supply  54  is connected to the remaining power terminals of the various gain stages within the RF amplifier  102  including the power terminal  108  of the final gain stage  106  providing supply currents to the gain stages including a supply current, I SF , to the final gain stage  106 . 
     The signal processor  80  determines, scales, and integrates the difference between the control tracking signal, S TRK-C , and the supply current tracking signal, S TRK-ISP , to obtain the gate biasing signal, S G , on the output terminal  87  of the signal processor  80 . The gate biasing signal, S G , is fed into a control terminal  112  of the RF amplifier  102 . The control terminal  112  of the RF amplifier  102  is coupled with the gate of the preceding gain stage  104  and gate of the final gain stage  106 . In another embodiment, control terminal  112  of the RF amplifier is solely coupled with the gate of the preceding gain stage  104 . Preferably, the RF amplifier  102  is characterized with a relatively constant gain over a usefully wide range of supply currents. In addition, it is desirable that mirroring between the preceding gain stage  104  and the final gain stage  106  remains constant. 
     In the adaptable supply current circuit  100 , the power expended in the control loop  78  is minimized. The sampling occurs in the preceding gain stage  104 , which typically operates on a power level and current much less than that of the final gain stage  106 . In another embodiment, the supply current, I SF , in the final gain stage  106  rather than the supply current, I SP , in the preceding gain stage  104  is detected. 
     Particular aspects of the adaptable supply current circuit  100  will now be described with reference to FIGS. 7,  8 , and  9 . The particular aspects of the adaptable supply current circuit  100  are arranged and designed to be used in a handset or Wireless Local Loop (WLL) terminal in a wireless communication system. The components shown in FIGS. 7,  8 , and  9  are represented using standard electrical symbology. The typical values and models of the respective components disclosed herein are based on an amplifier operating frequency of 1880 MHZ. It should be noted that these value and model specifications only aid in the understanding of the invention and do not in any way limit the invention. 
     Referring to FIG. 7, the power supply  54  has an output voltage of 5 volts on the output terminal  55  and is employed within the adaptable supply current circuit  100  to bias various components with a DC voltage of either 5 volts or 2.7 volts. Those components that are biased with 5 volts are connected directly to the power supply  54 , and those that are biased with 2.7 volts are connected to the power supply  54  through a voltage converter (not shown). A second power supply (not shown) having an output voltage of −5 volts is also connected within the adaptable supply current circuit  100  to bias various components with a DC voltage of −5 volts. The particular DC bias voltage values may vary from those disclosed herein and will depend on the particular application of this invention. 
     A driver  101  drives the RF amplifier  102 . The driver  101  includes a power terminal  124  connected to the power supply  54  through a switch SW 1  operated by the controller  60 . The driver  101  is enabled through a control terminal  126  connected to the controller  60  (connection not shown). The driver  101  further includes an RF input terminal  128  that receives the RF input signal, RF in , from processing circuitry (not shown) external to the adaptable supply current circuit  100 . The driver  101  amplifies the RF input signal, RF in , outputting an intermediate RF signal, RF in ′, on the RF output terminal  130  of the driver  101 . The particular aspects of the driver  101  are in accordance with typical known drivers. 
     The output terminal  130  of the driver  101  is connected to input terminal  120  of the RF amplifier  102 , and the intermediate RF signal, RF in ′, is applied to the RF input terminal  120  of the RF amplifier  102 . The RF amplifier  102  amplifies the intermediate RF signal, RF in ′, outputting the RF output signal, RF out , on the RF output terminal  122  of the RF amplifier  102 . The power terminal  108  of the preceding gain stage  104  of the RF amplifier  102  is coupled to the power supply  54  through the current detector  58  and switch SW 1 . The power terminal  110  of the final gain stage  106  of the RF amplifier  102  is connected to the power supply  54  through the switch SW 1 . The RF amplifier  102  includes a control terminal  112  that is electrically coupled to the power terminal  108  of the preceding gain stage  104  through the feedback control loop  78 . 
     A particular embodiment of the RF amplifier  102 , which has two gain stages, i.e., the preceding gain stage  104  and the final gain stage  106 , is shown in FIG.  8 . The gain stages are preferably embodied in an integrated chip  132 , which in this particular embodiment is a model PM2105 amplifier chip. The −5 volt DC bias is connected to the RFIN pin of the chip  132  through resistors R 1 , R 2 , R 3 , R 4 , and R 5 , and the VGG pin of the chip  132  through resistors R 1  and R 2 , providing a scaling factor for the biasing of the respective gates  114  and  116  of the preceding gain stage  104  and final gain stage  106 . 
     A decoupling capacitor Cl is connected between the −5 volt DC bias and ground to prevent high frequency signals from entering the second power supply (not shown). A diode D 1  is connected across resistors R 2  and R 3  to scale the current going into the respective power terminals  108  and  110  of the preceding gain stage  104  and final gain stage  106 . The values of resistors R 1 , R 2 , R 3 , R 4 , and R 5  are selected so that the desired absolute and relative amount of DC bias voltage is applied to the respective gates  104  and  106  of the preceding gain stage  114  and final gain stage  116 . 
     The power terminal  108  is connected to the VDD pin of the chip  132 , producing the supply current, I SP , in the preceding gain stage  104 . A low pass filter  134  is connected between the power terminal  108  and the VDD pin of the chip  132 . The low pass filter  134  preferably includes a parallel bank of grounded capacitors C 2 , C 3 , and C 4  and an inductor L 1  connected between the capacitors C 3  and C 4 . 
     The power terminal  110  is connected to the RFOUT 1  pin of the chip  132  through a low pass filter  136 , producing the supply current, I SF , in the final gain stage  106 . The low pass filter  136  preferably includes a parallel bank of grounded capacitors C 5 , C 6 , C 7 , and C 8  with transmission line sections TR 1 , TR 2 , TR 3 , and a resistor R 6  connected respectively between the RFOUT 1  pin and C 5 , C 5  and C 6 , C 6  and C 7 , and C 7  and C 8 . A decoupling capacitor C 9  is connected between the power supply  54  and ground. 
     The RF input terminal  120  of the RF amplifier  102  is connected to the RFIN terminal of the chip  132  through a coupling capacitor C 10  and the resistor R 5 . The RF output terminal  122  of the RF amplifier  102  is connected to the RFOUT 1  pin of the chip  132  through a matching circuit  138  and a DC blocking capacitor C 11 . The matching circuit  138  includes a parallel bank of grounded capacitors C 12 , C 13 , and C 14  with a transmission line section TR 4  connected between capacitors C 13  and C 14 . 
     The control terminal  112  of the RF amplifier  102  is connected to the RFIN pin of the chip  132  through a low pass filter  140  and the resistor R 5 . The control terminal  112  of the RF amplifier  102  is also connected to the VGG pin of the chip  132  through the resistor R 3 . The respective gates  114  and  116  of the preceding gain stage  104  and final gain stage  106  are dynamically biased with voltages that are proportional to the gate biasing voltage, V G , applied to the control terminal  112  via the control loop  78 . The low pass filter  140  rejects the RF input signal, RF in , and includes a transmission line section TR 5 , the resistor R 4 , and a capacitor C 15 . A pair of decoupling capacitors C 16  and C 17  are connected in parallel between the VGG pin of the chip  132  and ground. The values of the resistors R 1 , R 2 , R 3 , R 4 , and R 5  are selected to provide the desired absolute and relative amount of variable voltage that the respective gates  114  and  116  of the preceding gains stage  104  and final gain stage  106  are biased with. 
     The diode D 1  in this particular embodiment is a model BAV70 diode. Typical resistance values that may be used for the respective resistors R 1 -R 5  are e.g., 300Ω, 47Ω, 47Ω, 47Ω, and 3.3Ω. A typical resistance value that can be used for resistor R 6  is, e.g., 0.1Ω. The following typical capacitance values can be used, e.g.,: 0.1 μF for capacitors C 1  and C 9 ; 33 pF for capacitors C 2 -C 7 ; 1.5 pF for capacitors C 12 -C 14 ; 18 pF for capacitors C 15 -C 17 ; 1000 pF for capacitor C 8 ; and 27 pF for capacitor C 10 ; and 6.8 pF for capacitor C 11 . A typical inductance value of, e.g., 39nH can be used for the inductor L 1 . The following typical transmission line dimensions in mils, assuming 14 mil Getek material, can be used, e.g.,: 15W and 345L for TR 1 ; 15W and 49L for TR 2 ; 15W and 49L for TR 3 ; 27W and 288L for TR 4 ; and 27W and 202L for TR 5 . 
     An alternate embodiment of the RF amplifier  102 , which has three gain stages, i.e., a first gain stage  103 , the preceding gain stage  114 , and the final gain stage  116 , is shown in FIG.  9 . All three of the gain stages are embodied in a chip  142 , which in this particular embodiment is a model CM1335 amplifier chip. 
     The RF amplifier  102  has an additional power terminal  107  that is connected to the power supply  54  through the switch SW 1 . The power terminal  107  is in turn connected to the VD 1  pin of the chip  142  through a low pass filter  144 , producing a supply current in the first gain stage  103 . The low pass filter  144  includes a parallel bank of grounded capacitors C 18 , C 19 , and C 20  with an inductor L 2  connected between the capacitors C 19  and C 20 . 
     The power terminal  108  is connected to the VD 2  pin of the chip  142  through a low pass filter  146 , producing the biasing current, I SP , in the preceding gain stage  104 . The low pass filter  146  prevents high frequency signals from entering the first power supply  54  and comprises a parallel bank of grounded capacitors C 21  and C 22  with an inductor L 3  connected between the capacitors C 21  and C 22 . 
     The power terminal  110  is connected to the RFOUT 1  pin of the chip  142  through a low pass filter  148 , producing the biasing current, I SF , in the final gain stage  106 . The low pass filter  148  includes a parallel bank of grounded capacitors C 23 , C 24 , C 25 , and C 26  with transmission line sections TR 6 , TR 7 , TR 8 , and a resistor R 7  connected respectively between the RFOUT pin and C 23 , C 23  and C 24 , C 24  and C 25 , and C 25  and C 26 . A decoupling capacitor C 27  is connected between the power supply  54  and ground. 
     The RF input terminal  120  of the RF amplifier  102  is connected to the RFIN pin of the chip  142  through a resistor R 8 . A capacitor C 28  is grounded between the resistor R 8  and the RF input terminal  120 . The RF output terminal  122  of the RF amplifier  102  is connected to the RFOUT 1  pin of the chip  142  through a matching circuit  150  and a DC blocking capacitor C 29 . The matching circuit  150  comprises a parallel bank of grounded capacitors C 30  and C 31  with transmission line sections TR 9 , TR 10 , TR 11  connected respectively between the RFOUT pin and C 30 , C 30  and C 31 , and C 31  and the blocking capacitor C 29 . 
     The control terminal  112  of the RF amplifier  102  is connected to the VG 1  and VG 2  pins of the chip  142  through respective low pass filters  152  and  154 . The respective gates  114  and  116  of the preceding gain stage  104  and final gain stage  106  are dynamically biased with voltages that are proportional to the gate biasing voltage, V G , applied to the control terminal  112  via the control loop  78 . The low pass filter  152  prevents high frequency signals from entering the control loop  78  and comprises an inductor L 4  and a grounded capacitor C 32 . The low pass filter  154  prevents high frequency signals from entering the control loop  78  and comprises an inductor L 5  and a grounded capacitor C 33 . A resistor R 9  is connected between the control terminal  112  and ground. The value of the resistor R 9  is selected to provide the desired amount of dynamic voltage that the respective gates  114  and  116  of the preceding and final gain stages  104  and  106  are biased with. 
     Typical resistance values that may be used for the respective resistors R 7 -R 9  are, e.g., 0.1Ω, 2.2Ω, and 10 kΩ. The following typical capacitance values can be used, e.g.,: 33 pF for capacitors C 18 , C 20 , and C 22 ; 4700 pF for capacitor C 19 ; 100 pF for capacitor C 21 ; 27 pF for capacitors C 23 -C 25  and C 29 ; 1000 pF for capacitor C 26 ; 0.1 μF for capacitor C 27 ; 2.2 pF for capacitor C 28 ; 3.9 pF for capacitor C 30 ; 0.5 pF for capacitor C 31 ; and 18 pF for capacitors C 32  and C 33 . A typical inductance value of, e.g., 47 nH can be used for inductors L 2  and L 3 , and an inductance value of, e.g., 39 nH can be used for inductors L 4  and L 5 . The following typical transmission line dimensions in mils, assuming 14 mil Getek material, can be used, e.g.,: 15W and 720L for TR 6 ; 15W and 99L for TR 7 ; 15W and 99L for TR 8 ; 36W and 47L for TR 9 ; 17W and 157L for TR 10 ; and 17W and 147L for TR 11 . 
     As shown in FIG. 7, the current detector  58  is a current mirror, which employs a PNP bipolar transistor Q 1  and a diode D 2  to sample the supply current, I SP , entering the preceding gain stage  104  of the RF amplifier  102 . The cathode of the diode D 2  is connected to the base of the transistor Q 1 . The anode of the diode D 2  is connected to the input terminal  82  of the current detector  58  through a resistor R 10 . The cathode of the diode D 2  is connected to the output terminal  83  of the current detector. The emitter of the transistor Q 1  is connected to the input terminal  82  of the current detector  58  through a resistor R 11 . The collector of the transistor Q 1  is connected to the coupling terminal  84  of the current detector  58  through a resistor R 12 . 
     The input terminal  82  of the current detector  58  is connected to the output terminal  55  of the power supply  54  through the switch SW 1 , and the output terminal  83  of the current detector  58  is connected to the power terminal  108  of the RF amplifier  102  to provide the supply current, I SP , to the preceding gain stage  104  of the RF amplifier  102 . A diode D 3  is connected in parallel with the resistor R 10  to limit the supply current, I SP . The value of resistor R 10  is selected to provide the desired maximum amount of supply current, I SP . 
     A sampled supply current, I SP ′, substantially proportional to the supply current, I SP , is produced in the resistor R 12 . A sampled supply current voltage, V ISP , is produced across the resistor R 12 . The values of resistors R 11  and R 12  are selected so that the desired amount of the supply current, I SP , is sampled. A decoupling capacitor C 34  is connected between the input terminal  82  of the current detector  58  and ground. 
     The diodes D 2  and D 3  in FIG. 7 are model BAV70 diodes. The bipolar transistor Q 1  in this particular embodiment is a model MMBT3640 transistor. Typical resistance values of the respective resistors R 10 -R 12  are, e.g., 47Ω, 47Ω, and 120Ω. A typical capacitance value for the capacitor C 34  is, e.g., 0.1 μF. The current detector  58  is not limited to the current mirror depicted in FIG. 7, and may include other types of current mirrors. 
     The current detector  58  is connected to a startup circuit  156 . The coupling terminal  84  is connected to the drain of a JFET transistor Q 2 . The source of the JFET transistor Q 2  is connected to ground. The drain of a JFET transistor Q 3  is connected to the drain of the JFET transistor Q 2  through a resistor R 13 . The source of the JFET transistor Q 3  is connected to the 2.7 volt DC bias. The gate of the JFET transistor Q 3  is grounded through a resistor R 14 . The gate of the JFET transistor Q 2  is connected to the control terminal  126  of the driver  101 , and the gate of the JFET transistor Q 3  is connected to the control terminal  126  of the driver  101  through a resistor R 15 . Prior to the enablement of the startup circuit  156 , a relatively large voltage appears between the drain and the source of the JFET transistor Q 2 . Subsequent to the enablement of the startup circuit  156  and during the operation of the feedback control loop  78 , a supply current tracking voltage, V TRK-ISP , is produced between the drain and the source of the JFET transistor Q 2 . 
     The values of the resistor R 13 , R 14 , and R 15  are selected to provide the desired amount of biasing for of the JFET transistors Q 2  and Q 3  of the startup circuit  156 . The JFET transistors Q 2  and Q 3  in this particular embodiment are respective model BSS123 and BSS84 transistors. A typical resistance value for the resistors R 13 -R 16  is, e.g., 10 kΩ. 
     The controller  60  includes a control processing unit  164  and a digital-to-analog converter  168 . The control processing unit  164  is electrically coupled to the digital-to-analog converter  168  through four digital lines  166  to allow selection of an analog control voltage, V C , which is produced on the output terminal  61  of the controller  60 . The N number of digital lines  166  allows the controller  60  to select from 2 n  discrete voltage levels, and in this particular embodiment, sixteen discrete voltage levels. 
     The output terminal  61  of the controller  60  is connected to a voltage buffer  170 . The voltage buffer  170  comprises a resistor R 16 , a resistor R 17 , and a capacitor C 35  connected in series between the output terminal  61  of the controller  60  and ground. A decoupling capacitor C 36  is connected between the output terminal  61  of the controller  60  and ground. Alternatively, a 2.7 volt or 5 volt DC bias can be applied to the voltage buffer  170 . Connection of the output terminal  61  of the controller  60  to the resistor R 16  produces a control tracking voltage, V TRK-C , across the resistor R 17  and capacitor C 35 . 
     The values of the resistors R 16  and R 17  are selected to produce the desired scaling factor for the control tracking voltage, V TRK-C . Typical resistance values of the respective resistors R 16  and R 17  are, e.g., 15 kΩ and 100Ω. The typical capacitance values of the respective capacitors C 35  and C 36  are, e.g., 12 pF and 0.1 μF. 
     The signal processor  80  is an integrating amplifier that embodies the subtractor  62 , amplifier  64 , and integrator  66 . The signal processor  80  includes as its platform a differential operational amplifier U 1 . The inverting input terminal of the differential operational amplifier U 1  is connected to an output terminal  176  of the differential operational amplifier U 1  through resistor R 20  and a capacitor C 39 , providing negative feedback to the differential operational amplifier U 1 . 
     The first input terminal  85  of the signal processor  80  is connected to the inverting input terminal of the differential operational amplifier U 1  through resistors R 18  and R 19 . The second input terminal  86  of the signal processor  80  is connected to the noninverting input terminal of the differential operational amplifier U 1 . The output terminal of the operational amplifier U 1  is connected to the output terminal  176  of the signal processor  80 . 
     The signal processor  80  further includes positive and negative power terminals  172  and  174  that are respectively connected to the positive and negative power terminals of the differential operational amplifier U 1 . The positive power terminal  172  of the signal processor  80  is connected to the 5 volt DC bias. Alternatively, the positive power terminal  172  of the signal processor  158  can be connected to the 2.7 volt DC bias. The negative power terminal  174  of the signal processor  158  is connected to the −5 volt DC bias. Decoupling capacitors C 37  and C 38  are respectively connected between the 5 volt DC bias and ground, and the −5 volt DC bias and ground. 
     The coupling terminal  84  of the current detector  80  is connected to the first input terminal  85  of the signal processor  80  outputting the supply current tracking voltage, V TRK-ISP , on the first input terminal  85  of the signal processor  80 . The voltage buffer  170  is connected to the second input terminal  86  of the signal processor  80  outputting the control tracking voltage, V TRK-C , on the second input terminal  86  of the signal processor  80 . The second input terminal  86  of the signal processor  80  is connected between the resistors R 16  and R 17  of the voltage buffer  170 . The signal processor  80  produces a gate biasing voltage, V G , on the output terminal  176  of the signal processor  80  equal to the integrated and scaled difference between the control tracking voltage, V TRK-C , and the supply current tracking voltage, V TRK-ISP . The value of the capacitor C 35  is selected to vary the compensation and response time of the feedback control loop  78 . 
     The differential operational amplifier U 1  in this particular embodiment is a model LM7121 operational amplifier. The values of the resistors R 18 -R 20  and capacitor C 39  are selected to provide the desired gain and integration for the signal processor  80 . Typical resistance values for the respective resistors R 18 -R 20  are, e.g., 100Ω, 3KΩ, and 100Ω. Typical capacitance values for the respective capacitors C 37 -C 39  are, e.g., 0.1 μF, 0.1 μF, and 32 pF. 
     The output terminal  176  of the signal processor  80  is connected to the control terminal  112  of the RF amplifier  102  through a low pass filter  178 . The low pass filter  178  includes a pair of series connected resistors R 21  and R 22  with a grounded capacitor C 40  connected between the resistors R 21  and R 22 . A diode D 4  is connected in parallel with the output terminal  176  to prevent the respective gates  114  and  116  of the preceding gain stage  104  and the final gain stage  106  from becoming more positively biased than the voltage drop across the diode D 4 . The gate biasing voltage, V G , is outputted to the control terminal  112  of the RF amplifier  102  through the low pass filter  178 . 
     The diode D 4  in this particular embodiment is a model MA4C5103C diode. A typical resistance value of the resistors R 21  and R 22  is, e.g., 10Ω. A typical resistance value of the capacitor C 40  is, e.g., 18 pF. 
     The following is a description of the operation of the adaptable supply current circuit  100 . The handset or WLL terminal receives the RF power designating signal, S RFOUT , designating the power level of the RF output signal, RF out . Prior to closure of the switch SW 1 , no current is flowing through the startup circuit  156 , and thus, a relatively high voltage appears between the drain and source of the JFET transistor Q 2 , which is applied to the first input terminal  85  of the signal processor  80 . A relatively low voltage appears across the output of the voltage buffer  170 , which is applied to the second input terminal  86  of the signal processor  80 . As such, a high negative voltage appears on the output terminal  176  of the signal processor  80 , maintaining the RF amplifier  102  in an off position. 
     When the handset is ready to transmit to the base station, the controller  60  enables the switch SW 1 , providing power to the driver  101  through the power terminal  124  and to the preceding gain stage  104  and final gain stage  106  of the RF amplifier  102  through the respective power terminals  108  and  110 . The controller  60  also enables the driver  101  through the control terminal  126 . Since the startup circuit  156  is connected to the control terminal  126 , the gates of the JFET transistors Q 2  and Q 3  are biased, allowing current to flow through the startup circuit  156 . The control terminal  126  of the driver  101  is preferably enabled approximately 200 ns after the switch SW 1  is closed. 
     The voltage between the drain and the source of the JFET transistor Q 2  is reduced. The voltage on the first input terminal  85  of the signal processor  80  decreases, creating a relatively low negative voltage on the output terminal  176  of the signal processor  80 . The RF amplifier  102  is turned on to produce the supply currents, I SP  and I SF , in the respective preceding and final gain stages  104  and  106 . 
     The supply current, I SP , flows through the diode D 2  of the current detector  58 . The sampled supply current, I SP ′, flows through the bipolar transistor Q 1 , producing the sampled supply current voltage, V ISP , across the resistor R 12 . The bias current, I SP , influences the supply current tracking voltage, V TRK-ISP , between the drain and source of the JFET transistor Q 2 . The supply current tracking voltage, V TRK-ISP , inversely varies with the supply current, I SP . That is, as the supply current, I SP , increases, the sampled supply current, I SP ′, increases, increasing the sampled supply current voltage, V ISP , across the resistor R 12 . An increase in the sampled supply current voltage, V ISP , correspondingly decreases the supply current tracking voltage, V TRK-ISP , between the drain and source of the JFET transistor Q 2 . Likewise, a decrease in the supply current, I SP , correspondingly decreases the supply current tracking voltage, V TRK-ISP . The supply current tracking voltage, V TRK-ISP , indicates the present level of the supply current, I SP . 
     The control processing unit  164  of the controller  60  receives the RF power designating signal, S RFOUT , from the input terminal  63  of the controller  60 , and accordingly sends a digital signal through the control lines  166  to the digital-to-analog converter  168  selecting the control voltage, V C . The digital-to-analog converter  168  produces the control voltage, V C , on the output terminal  61  of the controller  60 . The control voltage, V C , is applied to the voltage buffer  170  to influence the control tracking voltage, V TRK-C , across the resistor R 17  and capacitor C 35 . The control tracking voltage, V TRK-C , varies with the control voltage, V C . That is, as the control voltage, V C , increases, the control tracking voltage, V TRK-C , increases. Likewise, as the control voltage, V C , decreases, the control tracking voltage, V TRK-C , decreases. The control tracking voltage, V TRK-C , indicates the desired level of the supply current, I SF . 
     The supply current tracking voltage, V TRK-ISP , is applied to the first input terminal  85  of the signal processor  80 . The control tracking voltage, V TRK-C , is applied to the second input terminal  86  of the signal processor  80 . The signal processor  80  determines, scales, and integrates the difference between the control tracking voltage, V TRK-C , and the supply current tracking voltage, V TRK-ISP , to produce the gate biasing voltage, V G , on the output terminal  176  of the signal processor  80 . 
     The gate biasing voltage, V G , is then fed through the low pass filter  178  into the control terminal  112  of the RF amplifier  102 , which varies the supply current, I SP , and thus the supply current, I SF , according to the control voltage, V C , selected by the controller  60 . 
     The RF input signal, RF in , is fed into the RF input terminal  128  of the driver  101 , which amplifies the RF input signal, RF in , to produce the intermediate RF signal, RF in ′, on the output terminal  130  of the driver  101 . The intermediate RF signal, RF in ′, is fed into the RF input terminal  120  of the RF amplifier  102 , which amplifies the intermediate RF signal, RF in ′, to produce the RF output signal, RF out , on the RF output terminal  122  of the RF amplifier  102 . The RF input signal, RF in , is preferably applied to the RF input terminal  128  of the driver  101  preferably approximately 400 ns after the closure of the switch SW 1 . 
     The levels of the supply currents, I SP  and I SF , are chosen such that it has the minimum value necessary to maintain the RF amplifier  102  in a linear operating range across the full range of average RF output signal power, P out . As depicted in FIG. 10, the controller  60  is programmed with a matrix of average RF output signal power, P out , levels P 1 -P 16  and corresponding control voltage, V C , levels V C1 -V C16 . As can be seen from FIG. 10., each voltage, V C , levels is chosen such it is the minimum necessary to maintain linear operation of the RF output amplifier  102  on that particular average RF output signal power, P out , level. It should be noted that because the controller  60  can select from sixteen discrete control voltage, V C , levels, the range of average RF output signal power, P out , levels is divided into sixteen corresponding levels. The level of the control voltage, V C , corresponding to the particular level of the average RF output signal, P out , should be chosen, such that the levels of the supply currents, I SP  and I SF , are the minimum necessary to maintain linear operation of the RF amplifier on that particular level of average RF output signal power, P out . 
     When the controller  60  receives the RF power designating signal, S RFOUT , designating the desired level of average RF output signal power, P out , the controller  60  will select the corresponding level of control voltage, V C , from the matrix and set the values of the supply currents, I SP  and I SF , to the minimum level necessary to maintain linear operation of the RF amplifier  102 . For instance, if the level of the average RF output signal power, P out , is P 5 , the controller  60  will receive the RF power designating signal, S RFOUT , designating the level P 5  as the desired average RF output signal power, P out . The controller  60  will accordingly select V C5  as the level of the control voltage, V C , which is the minimum level of the control voltage, V C , necessary to maintain linear operation of the RF amplifier  102  on an average RF output signal power, P out , level of P 5 . If the controller  60  receives the RF power designating signal, S RFOUT , sent from the base station designating an increase in the average RF output signal power, P out , from the level P 5  to the level P 6 , the controller  60  will accordingly select V C6  as the level of the control voltage, V C , which is the minimum level of the control voltage, V C , necessary to maintain linear operation of the RF amplifier  102  on an average RF output signal power, P out , level of P 5 . Likewise, if the controller  60  receives the RF power designating signal, S RFOUT , designating a decrease in the average RF output signal power, P out , from the level P 5  to the level P 4 , the controller  60  will accordingly select V C4  as the level of the control voltage, V C , which is the minimum level of the control voltage, V C , necessary to maintain linear operation of the RF amplifier  102  on an average RF output signal power, P out , level of P 4 . 
     FIG. 11 shows a dynamically adaptable supply current circuit  200 . The dynamically adaptable supply current circuit  200  is similar to the adaptable supply current circuit  100  shown in FIG. 6, and to the extent the components of each are the same, the same reference numerals have been used. The dynamically adaptable supply current circuit  200  differs from the adaptable supply current circuit  100  in that the bias current, I SP , varies with the envelope of a modulated RF output signal, RF out , from the level set by the controller  60 , increasing the efficiency of the RF amplifier  102 . 
     The RF amplifier  102  as depicted in FIG. 11 has N gain stages. A single-stage RF amplifier, however, can be employed in this arrangement without straying from the principles taught by this invention. The RF input signal, RF in , fed into the RF input terminal  120  of the RF amplifier  102  is amplified to produce an intermediate RF output signal, RF out ′, on the RF output terminal  122  of the RF amplifier  102 , which is a modulated signal having an output envelope signal, S env , as depicted in FIG.  3 . 
     The control feedback loop  78  of the dynamically adaptable supply current circuit  200  includes a signal detector  202  to sample the output envelope signal, S env . The signal detector  202  includes an input terminal  204  connected to the RF output terminal  122  of the RF amplifier  102 . The signal detector  202  samples the output envelope signal, S env , from the intermediate RF output signal, RF out ′ on the output terminal  122  of the RF amplifier  122  and produces the RF output signal, RF out , on an output terminal  206  of the signal detector  202 . The signal detector  202  includes a coupling terminal  208  connected to the second input terminal  86  of the signal processor  80 . The signal detector  202  produces a sampled output envelope signal, S env ,′ on the coupling terminal  208  of the signal detector  202 , influencing a control and envelope tracking signal, S TRK-C-env , on the second input terminal  86  of the signal processor  80 . The control and envelope tracking signal, S TRK-C-env , indicates the present level of the output envelope signal, S env , as well as the desired average level of the supply current, I SF . An example of a device that can be used as the signal detector  202  is a directional coupler and peak detector. 
     Alternatively, as shown in. FIG. 12, the feedback control loop  78  includes a signal detector  210  with an input terminal  212  that is connected to the RF output terminal  122  of RF amplifier  102 , and an output terminal  59  that is connected to the second input terminal  86  of the signal processor  80 . The RF output signal, RF out , having an output envelope signal, S env , is produced on the RF output terminal  122  of the RF amplifier  102 . The signal detector  210  samples the output envelope signal, S env , on the input terminal  212  of the signal detector  210  and produces the sampled output envelope signal, S env , on the output terminal  214  of the signal detector  210 , influencing the control and envelope tracking signal, S TRK-C-env , on the second input terminal  86  of the signal processor  80 . An example of a device that can be used as the signal detector  210  is a peak detector. 
     The signal processor  80  determines, scales, and integrates the difference between the control and envelope tracking signal, S TRK-C-env , and the supply current tracking signal, to obtain a dynamic gate biasing signal, S DG , on the output terminal  112  of the signal processor  80 . The dynamic gate biasing signal, S DG , is fed into a control terminal  112  of the RF amplifier  102 . 
     The control loop  78  allows the average supply current, I SF , to be set by the controller  60 , while allowing the supply current, I SF , to also vary with the level of the output envelope signal, S env . 
     In alternative embodiments, a dynamically adaptable supply current circuit is created by foregoing the employment of the controller  60 . In this embodiment, the signal detector  202  is employed to produce an envelope tracking signal, S TRK-env , which indicates the present level of the output envelope signal, S env , on the second input terminal  86  of the signal processor  80 . A dynamic gate biasing signal, S DG , is produced on the output terminal  112  of the signal processor  80 , and applied to the control terminal  112  of the RF amplifier  102 , allowing the average supply current, I SF , to vary with the output envelope signal, S env . 
     Particular aspects of the dynamically adaptable supply current circuit  200  will now be described with reference to FIG.  13 . To the extent the particular aspects of the dynamically adaptable supply current circuit  200  are the same to those of the adaptable supply current circuit  100 , the same reference numerals have been used. 
     The particular signal detector  202  in this embodiment is a peak or envelope detector. The envelope detector  202  includes a directional coupler  216 . The input port and output port of the directional coupler  216  are respectively connected to the input terminal  204  and the output terminal  206  of the envelope detector  202 . The RF output signal, RF out ′, on the output terminal  122  of the RF amplifier  102  has an output envelope voltage, V env . The coupling port of the directional coupler  216  is connected to ground through a load resistor R 23 , producing a sampled signal, RF out ″, at the resistor R 23 . 
     The anode of a DC biased diode D 5  is connected to ground through the load resistor R 23  and a DC blocking capacitor C 41 , and the cathode of the diode D 5  is connected to ground through an RC circuit comprising a resistor R 24  connected in parallel with a capacitor C 42 . The 2.7 volt DC bias is applied to a power terminal  203  of the envelope detector  202 . The power terminal  203  of the envelope detector  202  is connected to the anode of the diode D 5  through a resistor R 25 . A sampled output envelope voltage, V env ′, proportional to the output envelope voltage, V env , is produced across the RC circuit, R 24  and C 42 . The values of the resistor R 24  and C 42  are selected to vary the time constant of the RC circuit. 
     The cathode of the diode D 5  is connected to the coupling terminal  208  of the envelope detector  202 . The coupling terminal  208  of the envelope detector  202  is connected to ground through a resistor R 26  and the resistor R 17  and capacitor C 35  of the voltage buffer  170 . A control and envelope tracking voltage, V TRK-C-env , is produced across the resistor R 17  and capacitor C 35  of the voltage buffer  170 , and thus the second input terminal  86  of the signal processor  80 . This signal is a summation of V C  and V env ′. 
     The directional coupler  216  in this particular embodiment is a model 550PBM directional coupler. The diode D 5  in this particular embodiment is a model MA4E1245KA diode. Typical resistance values that may be used for the respective resistors R 23 -R 26  are, e.g., 220Ω, 10 kΩ, 270 kΩ, and 10 kΩ. A typical capacitance value that may be used for the respective capacitors C 41  and C 42  are, e.g., 27 pF and 2 pF. 
     As shown in FIG. 14, the envelope detector  202  can alternatively comprise a temperature compensation circuit  220 . The temperature compensation circuit  220  includes a DC biased diode D 6  that is connected on its anode to a power terminal  222  of the envelope detector  202  through a resistor R 27 . The power terminal  222  of the envelope detector  202  is connected to the 2.7 volt DC bias. The cathode of the diode D 6  is connected to ground through a resistor R 28 , producing a temperature compensating voltage, V TMP , across the resistor R 28 . Preferably, the resistance values R 25  and R 24  are respectively equal to the resistance values of R 27  and R 28  and the characteristics of the diodes D 5  and D 6  are similar, so that the temperature compensating voltage, V TMP , and the sampled output envelope voltage, V env ′ vary the same over temperature. 
     The cathode of the diode D 6  is connected to an inverting input terminal of a differential operational amplifier U 2  through a resistor R 29 . The resistor R 26  is connected to the noninverting input terminal of differential operational amplifier U 2 . The inverting input terminal of the differential operational amplifier U 2  is connected to the output terminal of the differential operational amplifier U 2  through an electrical path comprising a resistor R 30 . 
     The positive power terminal of the differential operational amplifier U 2  is connected to the 5 volt DC bias. Alternatively, the positive power terminal can be connected to the 2.7 volt DC bias. The negative power terminal of the differential operational amplifier U 2  is connected to the −5 volt DC bias. Decoupling capacitors C 43  and C 44  are respectively connected between the 5 volt DC bias and ground, and the −5 volt DC bias and ground. 
     A temperature compensated output envelope voltage, V env ″, proportional to the output envelope voltage, V env , and stable over a range of temperatures, is produced on the output terminal of the differential operational amplifier U 2 . The resistance values of R 26  and R 29  are equal to provide accurate temperature compensation of the sampled output envelope voltage, V env ′. The output terminal of the differential operational amplifier U 2  is connected to the coupling terminal  208  of the envelope detector  202 . The coupling terminal  208  of the envelope detector  202  is grounded through a feed resistor R 31 , and the resistor R 17  and capacitor C 35  of the voltage buffer  170 . The control and envelope tracking voltage, V TRK-C-env , is produced across the resistor R 17  and capacitor C 35  of the voltage buffer  170 , and thus the second input terminal  86  of the signal processor  80 . This signal is the summation of V env ″ and V C . 
     The signal processor  80  produces a dynamic gate biasing voltage, V DG , on the output terminal  176  of the signal processor  80  equal to the scaled and integrated difference between the control and envelope tracking voltage, V TRK-C-env , and the supply current tracking voltage, V TRK-ISP . 
     The diode D 6  in this particular embodiment is a model NA4E1245KA diode. The differential operational amplifier U 2  in this particular embodiment is a model LM7121 operational amplifier. Typical resistance values that may be used for the respective resistors R 27 - 31  are, e.g., 270 kΩ, 10 kΩ, 10 kΩ, 10 kΩ, and 3.9 kΩ. A typical capacitance value that may be used for the respective capacitors C 43  and C 44  is, e.g., 0.1 μF. 
     The following description of the operation of the dynamically adaptable supply current circuit  200  is provided. To the extent that the operative aspects of the dynamically adaptable supply current circuit  200  are similar to those of the adaptable supply current circuit  100  described above, they will not be repeated. 
     After the supply currents, I SP  and I SF , have reached their desired set levels, and the modulated output signal, RF out , has reached the RF output terminal  122  of the RF amplifier  102 , the envelope detector  202  samples the intermediate RF output signal, RF out ′, and produces the sampled output signal, RF out ″, across the resistor R 23 . The envelope detector  202  produces the RF output signal, RF out , on the RF output terminal  122  of the envelope detector  202 . The diode D 5  and RC circuit detect the envelope voltage of the sampled output signal, RF out ″, and produce the sampled output envelope voltage, V env ′, across the resistor R 24 . 
     If the temperature compensating circuit  210  is employed, the differential amplifier U 2  determines the difference between the temperature compensating voltage, V TMP , and the sampled output envelope voltage, V env ′. The temperature compensating voltage, V TMP , varies the same amount with temperature as does the sampled output envelope voltage, V env ′, and the temperature created variations in the sampled output envelope voltage, V env ′, are effectively removed by the differential amplifier U 2  to produce the temperature compensated sampled output envelope voltage, V env ″. 
     Depending on whether the temperature compensating circuit  210  is employed, either the sampled output envelope voltage, V env ′, or the temperature compensated sampled output envelope voltage, V env ″, is applied to the voltage buffer  170 , influencing the control and envelope tracking voltage, V TRK-C-env , across the resistor R 17  and capacitor C 35 . The control and envelope tracking voltage, V TRK-C-env , varies with the output envelope voltage, V env . That is, as the output envelope voltage, V env , increases, the control and envelope tracking voltage, V TRK-C-env , increases. Likewise, as the output envelope voltage, V env , decreases, the control and envelope tracking voltage, V TRK-C-env , decreases. The control and envelope tracking voltage, V TRK-C-env , indicates the present level of the output envelope voltage, V env , as well as the desired average level of the supply current, I sf . 
     The supply current tracking voltage, V TRK-ISP , is applied to the first input terminal  85  of the RF amplifier  102 . The control and envelope tracking voltage, V TRK-C-env , is applied to the second input terminal  86  of the signal processor  80 . The signal processor  80  determines, scales, and integrates the difference between the control and envelope tracking voltage, V TRK-C-env , and the supply current tracking voltage, V TRK-ISP , to produce a dynamic gate biasing voltage, V DG , on the output terminal  176  of the signal processor  80 . The dynamic gate biasing voltage, V DG , and thus the supply currents, I SP  and I SF , track the output envelope voltage, V env . The efficiency of the RF amplifier  102  is improved because the supply current, I SF , varies with the instantaneous power variations associated with the RF output signal, RF out , maintaining minimum DC bias power for a specific RF output power. 
     Referring to FIG. 15, a dynamically adaptable supply voltage circuit  300  is employed to operate the RF amplifier  102  included in the dynamically adaptable supply voltage circuit  300  more efficiently and linearly by varying a supply voltage, V S , applied to the RF amplifier  102 . 
     The RF amplifier  102  as depicted in FIG. 15 has an N number of gain stages. A single stage RF amplifier, however, can be employed in this arrangement without straying from the principles taught by this invention. 
     The dynamically adaptable supply voltage circuit  300  includes a variable power supply  302 . As with the dynamically adaptable supply current circuit  200 , the RF input signal, RF in , fed into the RF input terminal  120  of the RF amplifier  102  is amplified, and the intermediate RF output signal, RF out ′, on the RF output terminal  122  of the RF amplifier  102  is a modulated signal having the output envelope signal, S env . 
     The variable power supply  302  includes an output terminal  317  connected to a power terminal  312  of the RF amplifier  102  to produce the supply voltage, V S , on the power terminal  312  of the RF amplifier  102 . The variable power supply  302  further includes a control terminal  310  that is employed to control a variable internal source voltage (not shown) in the variable power supply  302 . 
     The supply voltage, V S , is controlled through a feedback control loop  303  that includes a signal processor  305 , a voltage detector  304 , a controller  320 , and a signal detector, such as the signal detector  202  employed by the dynamically adaptable supply current circuit  200 . 
     The voltage detector  304  includes an input terminal  313  connected to the power terminal  312  of the RF amplifier  102 , and an output terminal  315  connected to a second input terminal  309  of the signal processor  305 . The voltage detector  304  samples the supply voltage, V S , on the power terminal  312  of the RF amplifier  102  and producing a sampled supply voltage signal, S VS , on the output terminal  315  of the voltage detector  304 , influencing a supply voltage tracking signal, S TRK-VS , on the second input terminal  309  of the signal processor  305 . The supply voltage tracking signal, S TRK-VS , indicates the present level of the supply voltage, V S . An example of a device that can be used as the voltage detector  304  is a voltage divider. 
     Alternatively, as shown in FIG. 16, the feedback control loop  303  includes a voltage detector  322  with an input terminal  324  connected to the output terminal  317  of the variable power supply  302 , and an output terminal  326  connected to the power terminal  312  of the RF amplifier  102 . The voltage detector  322  samples the voltage on the input terminal  324  of the voltage detector  322  and produces the supply voltage, V S , on output terminal  326  of the voltage detector  322 , and thus the power terminal  312  of the RF amplifier  102 . The voltage detector further includes a coupling terminal  328  connected to the second input terminal  309  of the signal processor  305 . The voltage detector  322  produces a sampled supply voltage signal, S VS ,′ on the coupling terminal  328  of the voltage detector  322 , influencing the supply voltage tracking signal, S TRK-VS , on the second input terminal  309  of the signal processor  305 . An example of a device that can be used as the voltage detector  322  is a resistor network. 
     The controller  330  includes an input terminal  334  into which an RF power designating signal, S RFOUT , designating a desired average RF output signal power, P out , and thus, the desired supply voltage, V S , is input. The controller  330  further includes an output terminal  332  that is connected to a first input terminal  307  of the signal processor  305 . The controller  330  produces a control signal, S C , on the output terminal  332  of the controller  330  in accordance with the RF power designating signal, S RFOUT , influencing a control and envelope tracking signal, S TRK-C-env , on the first input terminal  307  of the signal processor  305 . The control and envelope tracking signal, S TRK-C-env , indicates the desired average voltage level of the supply voltage, V S . 
     The input terminal  204  of the signal detector  202  is connected to the RF output terminal  122  of the RF amplifier  102 . The signal detector  202  samples the output signal envelope, S env , on the input terminal  204  of the signal detector  202 , producing the RF output signal, RF out , on the output terminal  206  of the signal detector  202 . The coupling terminal  208  of the signal detector  202  is connected to the first input terminal  307  of the signal processor  305 . The signal detector  202  produces the sampled output envelope signal, S env ,′ on the coupling terminal  208  of the signal detector  202 , influencing the control and envelope tracking signal, S TRK-C-env , on the first input terminal  307  of the signal processor  305 . The control and envelope tracking signal, S TRK-C-env , the present level of the output envelope signal, S env , as well as the desired level of the supply voltage, V S . Alternatively, the feedback control loop  305  comprises the signal detector  210  depicted in FIG. 12 to sample the output envelope signal, S env . 
     The signal processor  305  includes a subtractor  306  and an amplifier  308 . The subtractor  306  determines the difference between the control and envelope tracking signal, S TRK-C-env , and the supply voltage tracking signal, S TRK-VS . In alternative embodiments, the signal processor  305  also includes an integrator. The amplifier  308  is preferably employed to scale the difference between the control and envelope tracking signal, S TRK-C-env , and the supply voltage tracking signal, S TRK-VS . The gain of the amplifier  308  can be greater or less than unity. The signal processor  305  produces a dynamic biasing signal, S DB , on an output terminal  311  of the signal processor  305 . The output terminal  311  of the signal processor  305  is connected to the control terminal  310  of the variable power supply  302 . The dynamic biasing signal, S DB , is fed into the control terminal  310  of the variable power supply  302 . The subtraction and scaling steps are not limited to the particular order described above, and can be performed in any order or simultaneously to obtain the dynamic biasing signal, S DB . The output voltage of the variable power supply  302 , and the supply voltage, V S , will vary according to the value of the dynamic biasing signal, S DB . 
     The control loop  303  allows the average supply voltage, V S , to be set by the controller  330 , while allowing the supply voltage, V S , to also vary, either discretely or continuously, with the level of the output envelope signal, S env . 
     In alternative embodiments, an adaptable supply voltage circuit is created by foregoing the employment of the signal detector  202 . In this embodiment, the controller  330  is employed to produce a control tracking signal, S TRK-C , which indicates the desired average level of the supply voltage, V S , on the first input terminal  307  of the signal processor  305 . A biasing signal, S B , is produced on the output terminal  311  of the signal processor  305 , and applied to the control terminal  310  of the variable power supply  302 , allowing the average supply voltage, V S , to be set by the controller  330 . 
     In further alternative embodiments, a dynamically adaptable supply voltage circuit is created by foregoing the employment of the controller  330 . In this embodiment, the signal detector  202  is employed to produce an envelope tracking signal, S TRK-env , which indicates the present level of the output envelope signal, S env , on the first input terminal  307  of the signal processor  305 . A dynamic biasing signal, S DB , is produced on the output terminal  311  of the signal processor  305 , and applied to the control terminal  310  of the variable power supply  302 , allowing the average supply voltage, V S , to vary with the output envelope signal, S env . 
     Particular aspects of the dynamically adaptable supply voltage circuit  300  will now be described with reference to FIG.  17 . To the extent the particular aspects of the dynamically adaptable supply voltage circuit  300  are the same as those of the dynamically adaptable supply current circuit  200 , the same reference numerals have been used. 
     The controller  330  is configured in much the same manner as the controller  60  described with respect to FIG.  7 . As with the dynamically adaptable supply current circuit  200  depicted in FIG. 14, the dynamically adaptable supply voltage circuit  300  employs the envelope detector  202 , which is connected to the RF output terminal  122  of the RF amplifier  102  to produce the temperature compensated sampled output envelope voltage, V env ″, on the coupling terminal  208  of the envelope detector  202 . The particular aspects of the envelope detector  202  have been set forth above with respect to FIG.  14 . The voltage detector  304  is a voltage divider comprising a pair of resistors R 34  and R 35  connected in series between the input terminal  313  of the voltage detector  304  and ground. The input terminal  313  of the voltage detector  304  is connected to ground through the resistors R 34  and R 35 . The output terminal  315  of the voltage detector  304  is connected to ground through the resistor R 35 . 
     The signal processor  305  is a differential amplifier that embodies the subtractor  306  and the amplifier  308 . The signal processor  305  includes as its platform a differential operational amplifier U 3 . The first input terminal  307  of the signal processor  305  is connected to the noninverting input terminal of the differential operational amplifier U 1 . The second input terminal  309  of the signal processor  308  is connected to the inverting input terminal of the differential operational amplifier U 1 . The output terminal of the operational amplifier U 1  is connected to the output terminal  311  of the signal processor  305 . 
     The signal processor  305  further includes positive and negative power terminals  319  and  321  that are respectively connected to the positive and negative power terminals of the differential operational amplifier U 3 . The positive power terminal  319  of the signal processor  319  is connected to the 5 volt DC bias. Alternatively, the positive power terminal  319  of the signal processor  305  can be connected to the 2.7 volt DC bias. The negative power terminal  321  of the signal processor  305  is connected to the −5 volt DC bias. The decoupling capacitors C 45  and C 46  are respectively connected between the 5 volt DC bias and ground, and the −5 volt DC bias and ground. 
     In alternative embodiments, the signal processor  305  is an integrating amplifier. 
     The coupling terminal  208  of the envelope detection  202  and the output terminal  332  of the controller  330  are electrically coupled to the signal processor  305  through a voltage buffer  336  and a resistor R 32 . The first input terminal  307  of the signal processor  305  is grounded through a resistor R 33 . The values of the resistors R 32  and R 33  are selected to scale the temperature compensated sampled output envelope voltage, V env ″. A control and envelope tracking voltage, V TRK-C-env , is produced across the resistor R 33 , and thus the noninverting input terminal of the differential operational amplifier U 3 . This signal is a summation of V C  and V env ″. 
     The output terminal  315  of the voltage detector  304  is connected through a resistor R 36  to the second input terminal  309  of the signal processor  305 . A supply voltage tracking voltage, V TRK-VS , is produced on the second input terminal  309  of the signal processor  305 . The input terminal  313  of the voltage detector  304  is connected to the second input terminal of the signal processor  305  through a resistor R 37 . The voltage gain of the differential operational amplifier U 3  can be varied by selecting the values of the resistors R 36  and R 37 . 
     The signal processor  305  produces a dynamic biasing voltage, V DB , on the output terminal  311  of the signal processor  305  equal to the scaled difference between the control and envelope tracking voltage, V TRK-C-env , and the supply voltage tracking voltage, V TRK-VS . The output terminal  311  of the signal processor  305  is connected to the control terminal  310  of the variable power supply  302 . The dynamic biasing voltage, V DB , is outputted to the control terminal  310  of the variable power supply  302 . 
     The variable power supply  302  comprises a bank of batteries V BAT1 , V BAT2 , V BAT3 , and V BAT4  that represent an internal source voltage of the power supply. The batteries V BAT1 , V BAT2 , V BAT3 , and V BAT4  are connected in series to ground. The positive terminals of each of the batteries V BAT1 , V BAT2 , V BAT3 , and V BAT4  are respectively connected to the collectors of a bank of matched NPN bipolar transistors Q 4 , Q 5 , Q 6 , and Q 7 . Schottky power diodes D 7 , D 8 , and D 9  are respectively connected between the power terminals of V BAT1 , V BAT2 , and V BAT3  and the collectors of transistors Q 4 , Q 5 , and Q 6  to prevent the batteries from forward biasing the transistor base-collector junction. The emitter of the transistor Q 4  is connected to the power terminal of the RF amplifier  301 . The emitters of transistors Q 5 , Q 6 , and Q 7  are connected to the power terminal of the RF amplifier  301  through respective resistors R 38 , R 39 , and R 40 . The base of the transistor Q 4  is connected to the output terminal of the differential operational amplifier U 3 . The bases of the transistors Q 5 , Q 6 , and Q 7  are connected to the output terminal of the differential operational amplifier U 3  through respective resistors R 41 , R 42 , and R 43 . By selecting the values of the respective resistors R 41 , R 42 , and R 43 , the current flowing into the bases of the transistors Q 5 , Q 6 , and Q 7  can be adjusted to control the switching points of the transistors Q 5 , Q 6 , and Q 7 . Selection of the values of the resistors R 34  and R 35  in the voltage detector  304  will also affect the switching points of the transistors. The values of the resistors R 38 , R 39 , and R 40  are selected, so that only the resistor connected to the transistor that is on will carry a significant amount of current. 
     Typical resistance values that may be used for the respective resistors R 38 -R 43  are, e.g., 0.10Ω, 0.15Ω, 0.30Ω, 1.0Ω, 2.0Ω, and 9.7Ω. A typical voltage value for each of the batteries V BAT1 , V BAT2 , V BAT3 , and V BAT4  is, e.g. , 1.2V. 
     The following is a description of the operation of dynamically adaptable supply voltage circuit  300 . To the extent that the operative aspects of the dynamically adaptable supply voltage circuit  300  similar to those of the amplifier  200  have been described above, they will not be repeated below. 
     The controller  330  receives the RF power designating signal, S RFOUT , from the input terminal  334  of the controller  60 , and accordingly produces the control voltage, V C , on the output terminal  332  of the controller  330 . The control voltage, V C , is applied to the resistor R 33  through the voltage buffer  336 , influencing the control and envelope tracking voltage, V TRK-C-env . The control and envelope tracking voltage, V TRK-C-env , varies with the control voltage, V C . That is, as the control voltage, V C , increases, the control and envelope tracking voltage, V TRK-C-env , increases. Likewise, as the control voltage, V C , decreases, the control and envelope tracking voltage, V TRK-C-env , decreases. The control and envelope tracking voltage, V TRK-C-env , indicates the desired average level of the supply voltage, V S . 
     The envelope detector  202  samples the output envelope voltage, V env , on the RF output terminal  122  of the RF amplifier  102 , and produces the temperature compensated sampled output envelope voltage, V env ″, on the coupling terminal  208  of the envelope detector  202 . The temperature compensated sampled output envelope voltage, V env ″, is applied to the resistor R 33  through the voltage buffer  336 , influencing the control and envelope tracking voltage, V TRK-C-env , across the resistor R 33 . The control and envelope tracking voltage, V TRK-C-env , varies with the output envelope voltage, V env . That is, as the output envelope voltage, V env , increases, the control and envelope tracking voltage, V TRK-C-env , increases. Likewise, as the output envelope voltage, V env , decreases, the control and envelope tracking voltage, V TRK-C-env , decreases. The control and envelope tracking voltage, V TRK-C-env , indicates the present level of the output envelope voltage, V env , as well as the desired level of the supply voltage, V S . 
     The variable power supply  302  produces a supply voltage, V S , on the power terminal  312  of the RF amplifier  102 . The supply voltage, V S , is applied to the voltage detector  304 , producing the sampled supply voltage, V S ′, across the resistor R 35  of the voltage detector  304 . The supply voltage, V S , influences the supply voltage tracking voltage, V TRK-VS , across the resistors R 35  and R 36 . The supply voltage tracking voltage, V TRK-VS , varies with the supply voltage, V S . That is, as the supply voltage, V S , increases, the supply voltage tracking voltage, V TRK-VS , increases. Likewise, as the supply voltage, V S , decreases, the supply voltage tracking voltage, V TRK-VS , decreases. The supply voltage tracking voltage, V TRK-VS , indicates the present level of the supply voltage, V S . 
     The control and envelope tracking voltage, V TRK-C-env , is applied to the first input terminal  307  of the signal processor  305 . The supply voltage tracking voltage, V TRK-VS , is applied to the second input terminal  309  of the signal processor  305 . The signal processor  305  takes the difference between the control and envelope tracking voltage, V TRK-C-env , and the supply voltage tracking voltage, V TRK-VS , and is scaled to produce the dynamic biasing voltage, V DB , on the output terminal  311  of the signal processor  305 . The dynamic biasing voltage, V DB , is then fed into the control terminal  310  of the variable power supply  302 , biasing the bases of the respective transistors Q 4 , Q 5 , Q 6 , and Q 7 . The resistors R 41 , R 42 , and R 43  create an increasing amount of resistance between the respective bases of the transistors Q 5 , Q 6 , and Q 7  and the control terminal  310  of the variable power supply  302 . A decreasing amount of bias voltage is applied to the respective bases of the transistors Q 4 , Q 5 , Q 6 , and Q 7 . 
     As the level of the output envelope voltage, V env , and thus the level of the dynamic biasing voltage, V DB , increases from a relatively low level to a relatively high level, the transistors Q 4 , Q 5 , Q 6 , and Q 7  will sequentially turn on, thus sequentially turning on the batteries V BAT1 , V BAT2 , V BAT3 , and V BAT4 . Likewise, as the level of the output envelope voltage, V env , and thus the level of the dynamic biasing voltage, V DB , decreases from a relatively high level to a relatively low level, the transistors Q 7 , Q 6 , Q 5 , and Q 4  will sequentially turn off, sequentially turning off the batteries V BAT4 , V BAT3 , V BAT2 , and V BAT1 . Depending on the level of the dynamic biasing voltage, V DB , applied to the control terminal  310  of the variable power supply  302 , and based on an individual battery voltage of 1.2V, the internal source voltage produced by the bank of batteries V BAT1 , V BAT2 , V BAT3 , and V BAT4 , could be 1.2V, 2.4V, 3.6V, or 4.8V. The total voltage of the batteries vary discretely. In alternative embodiments, the total voltage of the batteries varies continuously. 
     The supply voltage, V S , that is applied to the power terminal  312  of the RF amplifier  102  is proportional to the dynamic biasing voltage, V DB , and thus the output envelope voltage, V env . The supply voltage, V S , will vary with the output envelope voltage, V env . When the power level of the RF output signal, RF out , is high, the level of the supply voltage, V S , will be correspondingly high. Likewise, when the power level of the RF output signal, RF out , is low, the level of the supply voltage, V S , will be correspondingly low. In this manner, efficient linear operation of the RF amplifier  102  is ensured. 
     Only the minimum number of batteries V BAT1 , V BAT2 , V BAT3 , and V BAT4  are employed to ensure that the supply voltage, V S , tracks the output envelope voltage, V env , and the dynamically adaptable supply voltage circuit  300  is more power efficient. It should be noted that the corresponding number of batteries and transistors can vary depending on the amount of efficiency required of the dynamically adaptable supply voltage circuit  300 . In general, the smaller the battery voltage step, the more power efficient the dynamically adaptable supply voltage circuit  300  becomes. The bandwidth of the feedback control loop  303  is preferably greater than the maximum frequency of the RF signal envelope to allow the switching capability of the variable power supply  302  to properly track the output envelope voltage, V env . 
     Co-pending application Ser. No. 09/089,811, which is directed to a dynamically adaptable supply voltage circuit, is filed concurrently herewith and fully incorporated herein by reference. 
     The supply voltage, V S , varying capability of the dynamically adaptable supply voltage circuit  300  can be combined with the supply current, I S , varying capability of the dynamically adaptable supply current circuit  200  to form a dynamically adaptable supply current and voltage circuit  400  as generally depicted in FIG.  18 . To the extent the components of the dynamically adaptable supply current and voltage circuit  400  are the same as those of the dynamically adaptable supply current circuit  200  and dynamically adaptable supply voltage circuit  300  respectively depicted in FIGS. 11 and 15, the same reference numerals have been used. 
     The dynamically adaptable supply current and voltage circuit  400  employs the feedback control loop  78  of the dynamically adaptable supply current circuit  200  to vary the supply current, I SP  and I SF , in the respective preceding gain stage  104  and final gain stage  106  of the RF amplifier  102 . 
     The output terminal  317  of the variable power supply  302  is connected to the power terminal  110  of the final gain stage  106  of the RF amplifier  102  producing the supply current, I SF , in the final gain stage  106 , and the supply voltage, V S , on the power terminal  110  of the final gain stage  106 . The input terminal  82  of the current detector  58  is connected to the output terminal  317  of the variable power supply  302 , and the output terminal  83  of the current detector  58  is connected to the power terminal  108  of the preceding gain stage  104 , producing the supply current, I SP , in the preceding gain stage  104  of the RF amplifier  102 . The coupling terminal  84  of the current detector  58  is connected to the first input terminal  85  of the signal processor  80 . The current detector  58  produces the sampled supply current signal, S ISP , on the coupling terminal  84  of the current detector  58 , influencing the supply current tracking signal, S TRK-ISP , on the first input terminal  85  of the signal processor  80 . 
     A controller  402  similar to the controllers  60  and  330  described above, produces a control signal, S C1 , on an output terminal  404  of the controller  400  in accordance with an RF power indicating signal, S RFOUT , applied on an input terminal  408  of the controller  402 , influencing a control and envelope tracking signal, S TRK-C-env1 , on the second input terminal  86  of the signal processor  80 . 
     The input terminal  204  of the signal detector  202  is connected to the RF output terminal  122  of the RF amplifier  102  producing the RF output signal, RF out , on the output terminal  206  of the signal detector  202 . The coupling terminal  208  of the signal detector  202  is connected to the second input terminal  86  of the signal processor  80 . The signal detector  202  produces the sampled output envelope signal, S env ′, on the coupling terminal  208  of the signal detector  202 , influencing the control and envelope tracking signal, S TRK-C-env , on the second input terminal  86  of the signal processor  80 . The output terminal  61  of the controller  60  is connected to the second input terminal  86  of the signal processor  80 . 
     The signal processor  80  determines, scales, and integrates the difference between the control and envelope tracking signal, S TRK-C-env1 , and the supply current tracking signal, S TRK-ISP , to produce a dynamic gate biasing signal, S DG1 , on the output terminal  87  of the signal processor  80 . The output terminal  87  of the signal processor  80  is connected to the control terminal  112  of the RF amplifier  102 , producing the dynamic gate biasing signal, S DG1 , on the control terminal  112  of the RF amplifier  102 . The supply currents, I SP  and I SF , are set to a desired level by the controller  402  and vary from that level with the output envelope signal, S env . 
     The dynamically adaptable supply current and voltage circuit  400  also employs the variable power supply  302  and feedback control loop  303  of the dynamically adaptable supply voltage circuit  300  to vary the supply voltage, V S . 
     The input terminal  313  of the voltage detector  304  is connected to the output terminal  317  of the variable power supply  302  and the output terminal  315  of the voltage detector  304  is connected to the second input terminal  309  of the signal processor  305 . The voltage detector  304  produces the sampled supply voltage signal, S VS , on the output terminal  315  of the voltage detector  304 , influencing the supply voltage tracking signal, S TRK-VS , on the second input terminal  309  of the signal processor  305 . 
     The controller  402  produces a control signal, S C2 , on an output terminal  406  of the controller  400  in accordance with the RF power indicating signal, S RFOUT , applied on the input terminal  408  of the controller  402 , influencing a control and envelope tracking signal, S TRK-C-env2 , on the first input terminal  307  of the signal processor  305 . 
     The coupling terminal  208  of the signal detector  202  is also connected to the first input terminal  307  of the signal processor  305 , influencing the control and envelope tracking signal, S TRK-C-env2 , on the first input terminal  307  of the signal processor  305 . 
     The signal processor  305  determines and scales the difference between the control and envelope tracking signal, S TRK-C-env2 , and the supply voltage tracking signal, S TRK-VS , to produce a dynamic gate biasing signal, S DG2 , on the output terminal  311  of the signal processor  305 . The output terminal  311  of the signal processor  305  is connected to the control terminal  310  of the variable power supply  302 . The dynamic gate biasing signal, S DG2 , is produced on the control terminal  310  of the variable power supply  302 . The supply voltage, V S , is set to a desired level by the controller  402  and varies from that level with the output envelope signal, S env . 
     Operation of the dynamically adaptable supply current and voltage circuit  400  is similar to that of the dynamically adaptable supply current circuit  200  and dynamically adaptable supply voltage circuit  300 . The supply currents, I SP  and I SF , and the supply voltage, V S , can be independently controlled by the respective control loops  78  and  303 . 
     With respect to the adaptable supply current circuit  100 , dynamically adaptable supply current circuit  200 , dynamically adaptable supply voltage circuit  300 , and the dynamically adaptable supply current and voltage circuit  400 , variation of the RF amplifier supply current and/or the supply voltage creates a phase shift in the RF output signal, RF out , at the output of the RF amplifier, which manifests itself as phase distortion in phase modulated signals. To compensate for this phase distortion, the phase distortion of the RF output signal, RF out , can be determined and compensated for by altering (i.e., predistorting) the RF signal prior to its arrival at the RF amplifier. 
     As shown in FIG. 19, a bypassable circuit  500  is employed to operate an RF amplifier more efficiently and linearly by operating the RF amplifier only during a high RF output power condition, i.e., a condition wherein the RF amplifier is employed to produce a relatively high RF output signal power, P out , and bypassing the RF amplifier during a low RF output power condition, i.e., a condition wherein the RF amplifier is bypassed to produce a relatively low RF output signal power, P out . To the extent that the bypassable circuit  500  employs components that are similar to those of previous embodiments, the same reference numerals have been used. 
     The bypassable circuit  500  includes a first driver  504  and a second driver  506 , which act as pre-amplification means. An RF input signal, RF in , is fed into an RF input terminal  516  of the first driver  504  and an RF input terminal  518  of the second driver  506 . The first driver  504  includes an output terminal  520  connected to the RF input terminal  120  of the RF amplifier  102 . The second driver  506  includes an output terminal  522  connected to the RF output terminal  122  of the RF amplifier  102 . The particular aspects of the drivers  504  and  506  are in accordance with typical known drivers. 
     The bypassable circuit  500  further includes a controller  502 . The controller  502  includes an input terminal  524  into which a RF power designating signal, S RFOUT , indicating the existence of a high RF output power condition or a low RF output power condition, is input. The controller  502  includes a first output terminal  512  and a second output terminal  514 . The first output terminal  512  of the controller  502  is connected to a control terminal  508  of the first driver  504 , and the second output terminal  514  of the controller  502  is connected to a control terminal  510  of the second driver  506 . 
     A switch  528  is connected between the power supply  54  and the RF amplifier  102 . The switch  528  includes an input terminal  530  connected to the output terminal  55  of the power supply  54 , and an output terminal  532  connected to the power terminal  312  of the RF amplifier  102 . The switch  528  includes a control terminal  534  that allows the switch  528  to alternately open and close. The control terminal  534  of the switch  528  is connected to a third output terminal  526  of the controller  502 . 
     The following is a description of the operation of the bypassable circuit  500 . The handset or WLL terminal receives the RF power designating signal, S RFOUT , through the input terminal  524  of the controller  502 . During a high RF output power condition designated by the RF power designating signal, S RFOUT , the controller  502  produces a high select signal, S SEL1 , on the first output terminal  512  of the controller  502 , and a low select signal, S SEL2 , on the second output terminal  514  of the controller  502 . The high select signal, S SEL1 , is applied to the control terminal  508  of the first driver  504  to activate the first driver  504 . The low select signal, S SEL2 , is applied to the control terminal  510  of the second driver  506  to inactivate the second driver  506 . The controller  502  also produces a high switch signal, S SW , on the third output terminal  526  of the controller  502 . The high switch signal, S SW , is applied to the control terminal  534  of the switch  528 , closing the switch  528  and providing the flow of power from the power supply  54  to the RF amplifier  102 . 
     The first driver  504  amplifies the RF input signal, RF in , and produces an RF signal, RF in ″, on the RF output terminal  520  of the first driver  504 . The RF signal, RF in ″, is applied to the RF input terminal  120  of the RF amplifier  102 . The RF amplifier  102  amplifies the RF signal, RF in ″, and produces an RF output signal, RF out , on the RF output terminal  122  of the RF amplifier  102  that is effectively amplified by the first driver  504  and the RF amplifier  102 . 
     During a low RF output power condition designated by the RF power designating signal, S RFOUT , the controller  502  produces a high select signal, S SEL2 , on the second output terminal  514  of the controller  502 , and a low select signal, S SEL1 , on the first output terminal  512  of the controller  502 . The high select signal, S SEL2 , is applied to the control terminal  510  of the second driver  506  to activate the second driver  506 . The low select signal, S SEL1 , is applied to the control terminal  508  of the first driver  504  to inactivate the first driver  504 . The controller  502  also produces a low switch signal, S SW , on the third output terminal  526  of the controller  502 . The low switch signal, S SW , is applied to the control terminal  534  of the switch  528 , opening the switch  528  and impeding the flow of power from the power supply  54  to the RF amplifier  102 . 
     The second driver  506  amplifies the RF input signal, RF in , and produces the RF signal, RF in ″, on the RF output terminal  520  of the first driver  504 . The RF signal, RF in ″, is applied to the RF output terminal  122  of the RF amplifier  102 , producing an RF output signal, RF out , that is amplified solely by the second driver  506 . 
     Alternatively, the controller  502 , the respective drivers  504  and  506 , and the switch  528  can be configured so that the respective drivers  504  and  506  are activated by low select signals, S SEL1  and S SEL2 , rather than high select signals, S SEL1  and S SEL2 , and the switch  528  is closed by a low switch signal, S SW , rather than a high switch signal, S SW . 
     More alternatively, the controller  502  and the respective drivers  504  and  506  can be configured so that the respective drivers  504  and  506  are activated or inactivated by a single select signal, S SEL1 , produced on a single control terminal of the controller  502 . In this case, a component such as an inverter can be placed between the single control terminal of the controller  502  and one of the respective control terminals of the drivers  504  and  506 . If the inverter is placed between the signal control terminal of the controller  502  and the control terminal  510  of the second driver  506 , a high select signal, S SEL , produced on the single control terminal of the controller  502  produces a high select signal, S SEL , on the control terminal  508  of the first driver  504 , activating the first driver  504 , and produces a low select signal, S SEL , on the control terminal  510  of the second driver  506 , inactivating the second driver  506 . Contrariwise, a low select signal, S SEL , produced on the single control terminal of the controller  502  produces a high select signal, S SEL , on the control terminal  510  of the second driver  506 , activating the second driver  506 , and produces a low select signal, S SEL , on the control terminal  508  of the first driver  504 , inactivating the first driver  504 . 
     The RF amplifier  102  is only operated when a high power RF output signal, RF out , is required, conserving energy expended by the bypassable circuit  500  when a low power RF output signal, RF in , is required. 
     FIG. 20 shows a bypassable circuit  550 . The bypassable circuit  550  is similar to the bypassable circuit  500  shown in FIG. 19, and to the extent the components of each are the same, the same reference numerals have been used. The bypassable circuit  550  differs from the bypassable circuit  500  in that a third driver  552  and a fourth driver  554  are employed to provide an RF output signal, RF out , with a higher power level than that of the RF output signal, RF out , produced by the bypassable circuit  500 . 
     The third driver  552  includes an input terminal  556  connected to the output terminal  122  of the RF amplifier. The third driver  552  further includes a control terminal  560  connected to the first output terminal  512  of the controller  502 . The fourth driver  554  includes an input terminal  562  connected to the output terminal  522  of the second driver  506  and an output terminal  564  connected to an output terminal  558  of the third driver  552 . The fourth driver  554  further includes a control terminal  566  connected to the second output terminal  514  of the controller  502 . 
     The operation of the bypassable circuit  550  is similar to that of the bypassable circuit  500  with the exception that during a high RF output power condition, a high select signal, S SEL1 , is produced on the first output terminal  512  of the controller  502  activating the third driver  552  as well as the first driver  504 , and a low select signal, S SEL2 , is produced on the second output terminal  514  of the controller  502  inactivating the fourth driver  554  as well as the second driver  506 . An RF output signal, RF out , is produced on the output terminal  558  of the third driver  552  that has been amplified by the first driver  504 , the RF amplifier  102 , and the third driver  552 . Contrariwise, during a low RF output power condition, a high select signal, S SEL2 , is produced on the second output terminal  514  of the controller  502  activating the fourth driver  554  as well as the second driver  506 , and a low select signal, S SEL1 , is produced on the first output terminal  512  of the controller  502  inactivating the third driver  552  as well as the first driver  504 . An RF output signal, RFout, is produced on the output terminal  558  of the third driver  552  that has been amplified solely by the second driver  506  and the fourth driver  556 . 
     Co-pending application Ser. No. 09/080,812, which is directed to a bypassable circuit, is filed concurrently herewith and fully incorporated herein by reference. 
     The bypassable circuit  500  or bypassable circuit  550  can be employed to make the amplifier circuits  100 ,  200 ,  300 , or  400  respectively depicted in FIGS. 6,  11 ,  15 , and  18  more power efficient. 
     For instance, as depicted in FIG. 21, a switchable and dynamically adaptable supply current circuit  600  employs the bypassable circuit  500  as configured in FIG. 19, and the feedback control loop  78  as configured in FIG. 6 to operate the RF amplifier  102  during a high RF output power condition more efficiently and linearly by controlling the supply currents, I SP  and I SF , within the respective preceding stage  104  and final stage  106  of the RF amplifier  102 , while bypassing the RF amplifier  102  during a low RF output power condition. 
     The switchable and dynamically adaptable supply current circuit  600  includes a controller  602 . The controller  602  includes an input terminal  604  into which an RF power designating signal, S RFOUT , in input. The RF power designating signal, S RFOUT , indicates the existence of a high RF output power condition or a low RF output power condition, as well as the desired average RF output signal power, P out , and thus, the desired supply current, I S . The controller  602  includes a first output terminal  606  and a second output terminal  608 . The first output terminal  606  of the controller  602  is connected to the control terminal  508  of the first driver  504 , and the second output terminal  608  of the controller  602  is connected to the control terminal  510  of the second driver  506 . 
     The switch  528  is connected between the power supply  54  and the current detector  58  of the control feedback loop  78 . The input terminal  530  of the switch  54  is connected to the output terminal  55  of the power supply  54 , and the output terminal  532  of the switch  528  is connected to the input terminal  82  of the current detector  58 . The output terminal  532  of the switch  528  is also connected to the power terminal  110  of the final gain stage  106  of the RF amplifier  102 . The control terminal  534  of the switch  528  is connected to a third output terminal  610  of the controller  602 . 
     During a high RF output power condition, the controller  602  produces a high select signal, S SEL1 , on the first output terminal  606  of the controller  602 , and a low select signal, S SEL2 , on the second output terminal  608  of the controller  602  to activate the first driver  504  and inactivate the second driver  506 . The controller  602  also produces a high switch signal, S SW , on the third output terminal  610 . The high switch signal, S SW , is applied to the control terminal  534  of the switch  528 , closing the switch  528  and providing the supply current, I SP , in the preceding gain stage  104  of the RF amplifier  102 , and the supply current, I SF , in the final gain stage  106  of the RF amplifier  102 . The RF input signal, RF in , on the input terminal  516  of the first driver  504  is amplified through the first driver  504  and the RF amplifier  102  to produce the RF output signal, RF out , on the output terminal  122  of the RF amplifier  102 . 
     During a low RF output power condition, the controller  602  produces a high select signal, S SEL2 , on the second output terminal  608  of the controller  602 , and a low select signal, S SEL1 , on the first output terminal  606  of the controller  602  to activate the second driver  506  and inactivate the first driver  504 . The controller  602  also produces a low switch signal, S SW , on the third output terminal  610 . The low switch signal, S SW , is applied to the control terminal  534  of the switch  528 , opening the switch  528  and impeding the flow of power from the power supply  54  to the RF amplifier  102 . The RF input signal, RF in , on the input terminal  518  of the second driver  506  is amplified solely through the second driver  504  to produce the RF output signal, RF out , on the output terminal  122  of the RF amplifier  102  effectively bypassing the RF amplifier  102 . 
     During a high RF output power condition, the switchable and dynamically adaptable supply current circuit  600  employs the current detector  58 , signal detector  202 , and the signal processor  80  of the feedback control loop  78 , along with the controller  602 , to control the supply currents, I SP  and I SF , in the preceding gain stage  104  and final gain stage  106  of the RF amplifier  102 . The controller  602  includes a fourth output terminal  612  connected to the second input terminal  86  of the signal processor  80 . The controller  602  produces the control signal, S C , on the fourth output terminal  612  of the controller  602 , influencing the control and envelope tracking signal, S TRK-C-env , on the second input terminal  86  of the signal processor  80 . The control and envelope tracking signal, S TRK-C-env , is also influenced by the sampled envelope output signal, S env ′, produced on the coupling terminal  208  of the signal detector  202 . The supply current tracking signals, S TRK-ISP , on the first input terminal  85  of the signal processor  80  is influenced by the sampled supply current signal, S ISP , produced on the coupling terminal  84  of the current detector  58 , The signal processor  80  determines, scales, and integrates the difference between the supply current tracking signal, S TRK-ISP , and the control and envelope tracking signal, S TRK-C-env , to obtain the dynamic biasing gate signal, S DG , at the output terminal  112  of the signal processor  80 . The dynamic biasing gate signal, S DG , is applied to the control terminal  112  of the RF amplifier  102 , controlling the supply current, I SF , in the final gain stage  106  of the RF amplifier  102 . 
     As depicted in FIG. 22, a switchable and dynamically adaptable supply voltage circuit  700  employs and bypassable circuit  500  as configured in FIG. 19, and the feedback control loop  303  as configured in FIG. 15, to operate the RF amplifier  102  during a high RF output power condition more efficiently and linearly by controlling the supply voltage, VS, across the RF amplifier  120 , while allowing the RF Amplifier  102  to be bypassed during a low RF output power condition. 
     The switchable and dynamically adaptable supply voltage circuit  700  includes a controller  702 . The controller  702  includes an input terminal  704  into which an RF power designating signal, S RFOUT , in input. The RF power designating signal, S RFOUT , indicates the existence of a high RF output power condition or a low RF output power condition, as well as the desired average RF output signal power, P out , and thus, the desired supply voltage, V S . The controller  702  includes a first output terminal  706  and a second output terminal  708 . The first output terminal  706  of the controller  702  is connected to the control terminal  508  of the first driver  504 , and the second output terminal  708  of the controller  702  is connected to the control terminal  510  of the second driver  506 . 
     The switch  528  is connected between the variable power supply  302  and the RF amplifier  102 . The input terminal  530  of the switch  528  is connected to the output terminal  317  of the variable power supply  302 , and the output terminal  532  of the switch  528  is connected to the power terminal  312  of the RF amplifier  102 . The control terminal  534  of the switch  528  is connected to a third output terminal  710  of the controller  702 . 
     During a high RF output power condition, the controller  702  produces a high select signal, S SEL1 , on the first output terminal  706  of the controller  702 , and a low select signal, S SEL2 , on the second output terminal  708  of the controller  702  to activate the first driver  504  and inactivate the second driver  506 . The controller  702  also produces a high switch signal, S SW , on the third output terminal  710 . The high switch signal, S SW , is applied to the control terminal  534  of the switch  528 , closing the switch  528  and providing the supply voltage, V S , on the power terminal  312  of the RF amplifier  102 . The RF input signal, RF in , on the input terminal  516  of the first driver  504  is amplified through the first driver  504  and the RF amplifier  102  to produce the RF output signal, RF out , on the output terminal  122  of the RF amplifier  102 . 
     During a low RF output power condition, the controller  702  produces a high select signal, S SEL2 , on the second output terminal  708  of the controller  702 , and a low select signal, S SEL1 , on the first output terminal  706  of the controller  702  to activate the second driver  506  and inactivate the first driver  504 . The controller  702  also produces a low switch signal, S SW , on the third output terminal  710 . The low switch signal, S SW , is applied to the control terminal  534  of the switch  528 , opening the switch  528  and impeding the flow of power from the power supply  54  to the RF amplifier  102 . The RF input signal, RF in , on the input terminal  518  of the second driver  506  is amplified solely through the second driver  504  to produce the RF output signal, RF out , on the output terminal  122  of the RF amplifier  102 , effectively bypassing the RF amplifier  102 . 
     During a high RF output power condition, the switchable and dynamically adaptable supply current circuit  700  employs the signal detector  202 , voltage detector  304 , and signal processor  305  of the feedback control loop  303 , along with the controller  702 , to control the supply voltage, V S , on the power terminal  312  of the RF amplifier  102 . The controller  702  includes a fourth output terminal  712  connected to the first input terminal  307  of the signal processor  305 . The controller  702  produces the control signal, S C , on the fourth output terminal  712  of the controller  602 , influencing the control and envelope tracking signal, S TRK-C-env , on the first input terminal  307  of the signal processor  80 . The control and envelope tracking signal, S TRK-C-env , is also influenced by the sampled envelope output signal, S env ′, produced on the coupling terminal  208  of the signal detector  202 . The supply voltage tracking signal, S TRK-VS , on the second input terminal  309  of the signal processor  305  is influenced by the sampled supply voltage signal, S VS , produced on the output terminal  315  of the voltage detector  304 . The signal processor  305  determines and scales, and alternatively integrates, the difference between the control and envelope tracking signal, S TRK-C-env , and the supply voltage tracking signal, S TRK-VS , to obtain the dynamic gate biasing signal, S DG , at the output terminal  311  of the signal processor  305 . The dynamic gate biasing signal, S DG , is applied to the control terminal  310  of the variable power supply  302 , controlling the supply voltage, V S , on the power terminal  312  of the RF amplifier  102 . 
     As depicted in FIG. 23, a switchable and dynamically adaptable supply current and voltage circuit  800  employs the bypassable circuit  500  as configured in FIG. 19, the feedback control loop  78  as depicted in FIG. 6, and the feedback control loop  303  as configured in FIG. 15 to operate the RF amplifier  102  during a high RF output power condition more efficiently and linearly by controlling the supply currents, I SP  and I SF , within the preceding gain stage  104  and final gain stage  106  of the RF amplifier  102  and the supply voltage, V S , across the RF amplifier  102 , while allowing the RF amplifier  102  to be bypassed during a low RF output power condition. 
     The switchable and dynamically adaptable supply current and voltage circuit  800  includes a controller  802 . The controller  802  includes an input terminal  804  into which an RF power designating signal, S RFOUT , in input. The RF power designating signal, S RFOUT , indicates the existence of a high RF output power condition or a low RF output power condition, as well as the desired average RF output signal power, P out , and thus, the desired supply current, I S , and supply voltage, V S . The controller  802  includes a first output terminal  806  and a second output terminal  808 . The first output terminal  806  of the controller  802  is connected to the control terminal  508  of the first driver  504 , and the second output terminal  708  of the controller  702  is connected to the control terminal  510  of the second driver  506 . 
     The switch  528  is connected between the variable power supply  54  and the current detector  58  of the control feedback loop  78 . The input terminal  530  of the switch  54  is connected to the output terminal  317  of the variable power supply  302 , and the output terminal  532  of the switch  528  is connected to the input terminal  82  of the current detector  58 . The output terminal  532  of the switch  528  is also connected to the power terminal  110  of the final gain stage  106  of the RF amplifier  102 . The control terminal  534  of the switch  528  is connected to a third output terminal  810  of the controller  802 . 
     During a high RF output power condition, the controller  802  produces a high select signal, S SEL1 , on the first output terminal  806  of the controller  802 , and a low select signal, S SEL2 , on the second output terminal  808  of the controller  802  to activate the first driver S 04  and inactivate the second driver  506 . The controller  802  also produces a high switch signal, S SW , on the third output terminal  810 . The high switch signal, S SW , is applied to the control terminal  534  of the switch  528 , closing the switch  528  and providing the supply current, I SP , in the preceding gain stage  104  of the RF amplifier  102 , the supply current, I SF , in the final gain stage  106  of the RF amplifier  102 , and the supply voltage, V S , on the power terminal  110  of the final gain stage  106  of the RF amplifier  102 . The RF input signal, RF in , on the input terminal  516  of the first driver  504  is amplified through the first driver  504  and the RF amplifier  102  to produce the RF output signal, RF out , on the output terminal  122  of the RF amplifier  102 . 
     During a low RF output power condition, the controller  802  produces a high select signal, S SEL2 , on the second output terminal  808  of the controller  802 , and a low select signal, S SEL1 , on the first output terminal  806  of the controller  802  to activate the second driver  506  and inactivate the first driver  504 . The controller  802  also produces a low switch signal, S SW , on the third output terminal  810 . The low switch signal, S SW , is applied to the control terminal  534  of the switch  528 , opening the switch  528  and impeding the flow of power from the power supply  54  to the RF amplifier  102 . The RF input signal, RF in , on the input terminal  518  of the second driver  506  is amplified solely through the second driver  504  to produce the RF output signal, RF out , on the output terminal  122  of the RF amplifier  102 , effectively bypassing the RF amplifier  102 . 
     During a high RF output power condition, the switchable and dynamically adaptable supply current and voltage circuit  800  employs the current detector  58 , the signal detector  202 , and the signal processor  80  of the feedback control loop  78 , along with the controller  802  to control the supply current, I SF , in the final gain stage  106  of the RF amplifier  102 . The controller  602  includes a fourth output terminal  812  connected to the second input terminal  86  of the signal processor  80 . The controller  602  produces a control signal, S C1 , on the fourth output terminal  612  of the controller  602 , influencing the control and envelope tracking signal, S TRK-C-env , on the second input terminal  86  of the signal processor  80 . The control and envelope tracking signal, S TRK-C-env , is also influenced by the sampled envelope output signal, S env ′, produced on the coupling terminal  208  of the signal detector  202 . The supply current tracking signal, S TRK-ISP , on the first input terminal  85  of the signal processor  80  is influenced by the sampled supply current signal, S ISP , produced on the coupling terminal  84  of the current detector  58 . The signal processor  80  determines, scales, and integrates the difference between the supply current tracking signal, S TRK-ISP , and the control and envelope tracking signal, S TRK-C-env1 , to obtain the dynamic biasing gate signal, S DG1 , at the output terminal  112  of the signal processor  80 . The dynamic biasing gate signal, S DG1 , is applied to the control terminal  112  of the RF amplifier  102 , controlling the supply currents, I SP  and I SF , in the preceding gain stage  104  and final gain stage  106  of the RF amplifier  102 . 
     During a high RF output power condition, the switchable and dynamically adaptable supply current and voltage circuit  800  also employs the signal detector  202 , voltage detector  304 , and signal processor  305  of the feedback control loop  303 , along with the controller  802 , to control the supply voltage, V S , on the power terminal of the RF amplifier  102 . The controller  802  includes a fifth output terminal  814  connected to the first input terminal  307  of the signal processor  305 . The controller  802  produces the control signal, S C2 , on the fifth output terminal  814  of the controller  802 , influencing the control and envelope tracking signal, S TRK-C-env , on the first input terminal  307  of the signal processor  80 . The control and envelope tracking signal, S TRK-C-env2 , is also influenced by the sampled envelope output signal, S env ′, produced on the coupling terminal  208  of the signal detector  202 . The signal processor  305  determines, scales, and in alternative embodiments integrates, the difference between the control and envelope tracking signal, S TRK-C-env2 , and the supply voltage tracking signal, S TRK-VS , to obtain the dynamic gate biasing signal, S DG2 , at the output terminal  311  of the signal processor  305 . The dynamic gate biasing signal, S DG2 , is applied to the control terminal  310  of the variable power supply  302 , controlling the supply voltage, V S , on the power terminal  110  of the final gain stage  106  of the RF amplifier  102 . 
     As shown in FIG. 24, a bypassable circuit  900  is employed to operate an RF amplifier more efficiently and linearly by operating the RF amplifier only during a high RF output power condition, and bypassing the RF amplifier during a low RF output power condition. To the extent that the bypassable circuit  900  employs components that are similar to those of previous embodiments, the same reference numerals have been used. 
     The bypassable circuit  900  includes a first switch  904  having an input terminal  918  and an output terminal  920 , and a second switch  906  having an input terminal  924  and an output terminal  926 . The input terminal  918  and output terminal  920  of the first switch  904  are respectively connected to the RF output terminal  130  of the driver  101 , which acts as a pre-amplification means, and the RF input terminal  120  of the RF amplifier  102 . The input terminal  924  and output terminal  926  of the second switch  906  are respectively connected to the output terminal  130  of the driver  101  and an RF output terminal  946  of the amplifier circuit  900 . The first switch  904  and the second switch  906  respectively include control terminals  922  and  928  to allow the first switch  906  and the second switch  908  to alternately open and close. 
     A third switch  908  is connected between the power supply  54  and the RF amplifier  102 . The third switch  908  includes an input terminal  930  connected to the output terminal  55  of the power supply  54 , and an output terminal  932  connected to the power terminal  312  of the RF amplifier  102 . The third switch  936  includes a control terminal  942  that allows the third switch  936  to alternately open and close. 
     A fourth switch  936  is connected between the RF amplifier  102  and the external circuitry. The fourth switch  936  includes an input terminal  938  and an output terminal  940  that are respectively connected to the RF output terminal  122  of the RF amplifier  102  and the RF output terminal  946  of the amplifier circuit  900 . The fourth switch  936  includes a control terminal  942  to allow the fourth switch  936  to alternately open and close. 
     The bypassable circuit  900  further includes a controller  902 . The controller  902  includes an input terminal  924  into which a RF power designating signal, S RFOUT , indicating the existence of a high RF output power condition or a low RF output power condition, is input. The controller  902  includes a first output terminal  912  and a second output terminal  914 . The first output terminal  912  of the controller  902  is connected to the control terminal  922  of the first switch  904  and the control terminal  942  of the fourth switch  936 , and the second output terminal  914  of the controller  902  is connected to the control terminal  928  of the second switch  906 . The controller  902  further includes a third output terminal  916  connected to the control terminal  934  of the third switch  908 . 
     The following is a description of the operation of the bypassable circuit  900 . The handset or WLL terminal receives the RF power designating signal, S RFOUT , through an input terminal  944  of the controller  902 . During a high RF output power condition designated by the RF power designating signal, S RFOUT , the controller  902  produces a high select signal, S SEL1 , on the first output terminal  912  of the controller  902 , and a low select signal, S SEL2 , on the second output terminal  914  of the controller  502 . The high select signal, S SEL1 , is applied to the control terminal  922  of the first switch  904  and the control terminal  942  of the fourth switch  936 , thereby closing the first switch  904  and the fourth switch  936 . The low select signal, S SEL2 , is applied to the control terminal  928  of the second switch  906 , thereby opening the second switch  906 . The controller  902  also produces a high switch signal, S SW , on the third output terminal  916  of the controller  902 . The high switch signal, S SW , is applied to the control terminal  934  of the third switch  908 , thereby closing the third switch  908  and providing the flow of power from the power supply  54  to the RF amplifier  102 . 
     The driver  101  amplifies the RF input signal, RF in , and produces an RF signal, RF in ′, on the RF output terminal  130  of the driver  101 . The RF signal, RF in ′, passes through the closed first switch  904  and applied to the RF input terminal  120  of the RF amplifier  102 . The RF signal, RF in ′, however, does not pass through the open second switch  906 . The RF amplifier  102  amplifies the RF signal, RF in ′, and produces an RF output signal, RF out , on the RF output terminal  122  of the RF amplifier  102  that has been effectively amplified by the driver  101  and the RF amplifier  102 . The RF output signal, RF out , passes through the closed fourth switch  936  to the RF output terminal  946  of the amplifier circuit  900 . 
     During a low RF output power condition designated by the RF power designating signal, S RFOUT , the controller  902  produces a high select signal, S SEL2 , on the second output terminal  914  of the controller  902 , and a low select signal, S SEL1 , on the first output terminal  912  of the controller  902 . The high select signal, S SEL2 , is applied to the control terminal  928  of the second switch  906 , thereby closing the second switch  906 . The low select signal, S SEL1 , is applied to the control terminal  922  of the first switch  904  and the control terminal  942  of the fourth switch  936 , thereby opening the first switch  904  and the fourth switch  936 . The controller  902  also produces a low switch signal, S SW , on the third output terminal  916  of the controller  902 . The low switch signal, S SW , is applied to the control terminal  934  of the fourth switch  908 , opening the fourth switch  908  and impeding the flow of power from the power supply  54  to the RF amplifier  102 . 
     The driver  101  amplifies the RF input signal, RF in , and produces an RF signal, RF in ′, on the RF output terminal  130  of the driver  101 . The RF signal, RF in ′, does not pass through the open first switch  904  to the RF amplifier  102 , but rather passes through closed second switch  906 . The RF signal, RF in ′, is applied to the RF output terminal  946  of the amplifier circuit  900  as the RF output signal, RF out , which has effectively been solely amplified by the driver  101 . The open fourth switch  936  prevents the RF signal, RF out , from entering the RF amplifier  102  through the RF output terminal  122  of the RF amplifier  102 . 
     Alternatively, the controller  902  and the respective switches  904 ,  906 ,  908 , and  936  can be configured so that the respective switches  904 ,  906 , and  908  are closed by low select signals, S SEL1  and S SEL2 , rather than high select signals, S SEL1  and S SEL2 , and the switch  936  is closed by a low switch signal, S SW , rather than a high switch signal, S SW . 
     More alternatively, the controller  902  and the respective switches  904 ,  906 ,  908  are closed or opened by a single select signal, S SEL1 , produced on a single control terminal of the controller  902 . In this case, a component such as an inverter can be placed between the single control terminal of the controller  902  and the control terminals of the first switch  904  and second switch  906  or the control terminal of the third switch  908 . 
     The RF amplifier  102  is only operated when a high power RF output signal, RF out , is required, conserving energy expended by the bypassable circuit  900  when a low power RF output signal, RF in , is required. 
     Like the bypassable circuits  500  and  550 , the bypassable circuit  900  can be employed to make the amplifier circuits  100 ,  200 ,  300 , or  400  respectively depicted in FIGS. 6,  11 ,  15 , and  18  more power efficient. 
     Thus, an improved apparatus and method for improving the power efficiency and linearity of an RF amplifier is disclosed. The various components of the embodiments have been described as being connected to each other. Intermediate components, however, can be placed between those components described as being connected to each other to format the signal between the respective components without straying from the principles taught by this invention. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. 
     The invention, therefore is not to be restricted except in the spirit of the appended claims.