Abstract:
An object of the present invention is to provide a transmitter-receiver RF-IC having a built-in regulator, which can reduce a minimum value of an input voltage of the regulator without increasing its area, the input voltage being supplied from a battery, the transmitter-receiver RF-IC being capable of normal operation with the input voltage, whereby the operating time of a mobile terminal can be improved as compared with the prior art. 
     According to the present invention, in order to achieve the above object, an output end of a regulator built into a RF-IC is first led to the outside of the RF-IC. Then, the output end is led to an area in proximity to the circuit block by use of wiring on a mobile terminal substrate whose resistance is low, or by use of wiring on a module whose resistance is low, thereby shortening the wiring length inside the RF-IC.

Description:
CLAIM OF PRIORITY 
   The present application claims priority from Japanese application JP2004-303880, filed on Oct. 19, 2004, the content of which is hereby incorporated by reference into this application. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a transmitter-receiver with a built-in regulator used for a mobile terminal. 
   2. Description of the Related Arts 
     FIG. 7  is a block diagram illustrating how a GSM (Global System for Mobile communications)-capable mobile terminal is in general configured (for example, refer to  FIG. 5  in PCT Patent Laid-open No. WO01/052427). This mobile terminal includes: a base band (hereinafter referred to as “BB”)  102 ; a transmitter-receiver RF-IC (hereinafter referred to as “RF-IC”); a power amplifier (hereinafter, refer to as PA)  103 ; an SAW filter (hereinafter refer to as SAW)  104   e ; and an antenna switch (hereinafter referred to as “ASW”)  105 . The BB  102  subjects audio and data to proper signal processing such as encoding, error correction, or modulation and demodulation. The RF-IC subjects an IQ signal coming from the BB  102  to proper processing such as frequency conversion or amplification before outputs the signal to the PA  103 . In addition, the RF-IC receives as an input signal an output signal of the SAW  104   e  to subjects the input signal proper processing such as frequency conversion or amplification before outputs an IQ signal to the BB  102 . The PA  103  adds a proper gain to an output signal of the RF-IC. The SAW  104   e  suppresses unnecessary signals. The ASW  105  is used to properly connect the antenna  111  to the SAW  104   e  or the PA  103 . Since GSM applies the time-division multiplexing (TDMA) method, the antenna  111  is connected to an output end of the PA  103  at the time of transmission, whereas the antenna  111  is connected to an input end of the SAW  104  at the time of receiving. A voltage Vbat is applied to the power supply of the PA  103 . Usually, the voltage Vbat is directly supplied from a battery of the mobile terminal. Reference numeral  113   d  denotes a voltage stabilization regulator (hereinafter referred to as “regulator”). The regulator receives the voltage Vbat as an input voltage, and outputs a voltage that is suitable for the RF-IC  101 . For example, the regulator converts a value of the voltage Vbat from 5 V to 2.8 V before outputting the voltage Vbat. An output voltage of the regulator  113   d  is supplied through wiring  502  to circuit blocks  500   a ,  500   b  inside the RF-IC  101 . The wiring  502  includes wiring on a mobile terminal substrate, and wiring inside IC. As shown in the figure, power supply wiring of the circuit block  500   a  and that of the circuit block  500   b  are separately led out from the RF-IC  101  to the outside so that the length of the wiring inside IC becomes as short as possible. 
   In recent years, mobile terminals require not only basic functions as a telephone but also additional functions including data communications, a camera function, and a bluetooth function. For this reason, further miniaturization is required for each part constituting a mobile terminal. The RF-IC has been improved in integration degree in order to satisfy the requirement of miniaturization. 
   SUMMARY OF THE INVENTION 
     FIG. 8  is a diagram illustrating as an example a configuration used to achieve a further improvement in integration degree of a RF-IC on the basis of the configuration of the general mobile terminal shown in  FIG. 7 . A regulator  113   e  is integrated into the RF-IC  101 . From the regulator  113   e  built into the RF-IC, the power supply is supplied to circuit blocks  500   a ,  500   b  inside the RF-IC  101  by use of wiring  600  inside the RF-IC  101 . 
   In  FIG. 8 , the distance from the regulator  113   e  to the circuit block  500   b  is long, which causes a value of the wiring resistance to increase. As a result, the voltage drop in wiring becomes larger. For example, on the assumptions that the current consumption of the circuit block  500   b  is 120 mA, and that the wiring resistance between the regulator  113   e  and the circuit block  500   b  is 5Ω, the voltage drop is calculated as follows: 120 mA×5=0.6 V. On the other hand, the wiring between the regulator  113   d  and the circuit block  500   b  in  FIG. 7  includes, for the most part, wiring on the mobile terminal whose resistance is small. Accordingly, because wiring inside the RF-IC  101  is short, the wiring resistance of the wiring between the regulator  113   d  and the circuit block  500   b  is smaller than that between the regulator  113   e  and the circuit block  500   b . For example, the wiring resistance is 1Ω. Therefore, the voltage drop is calculated as follows: 120 mA×1=0.12 V. Since the voltage Vbat is usually an output voltage of a battery, its value decreases when the mobile terminal is used. As described above, with reference to  FIGS. 7 and 8 , the difference in voltage drop caused by the wiring resistance is 0.48 V (=0.6 V−0.12 V). On the assumption that the RF-IC  101  is capable of normal operation with the voltage Vbat whose value is 3 V or more in  FIG. 7 , the RF-IC  101  is capable of normal operation only with the voltage Vbat whose value is 3.48 V (=3 V+0.48 V) or more in the case of the configuration in  FIG. 7 . Therefore, the configuration in  FIG. 7  produces a problem in that the operating time of the mobile terminal is shortened. In addition, if the width of the wiring is increased to reduce the wiring resistance inside the RF-IC  101 , the area of the RF-IC  101  is increased, leading to another problem of higher costs. 
   An object of the present invention is to solve the above problems, and to achieve the miniaturization of a RF-IC with a built-in regulator without the operating time of a mobile terminal being shortened. 
   According to the present invention, in order to solve the above problems, an output end of a regulator built into a RF-IC is first led to the outside of the RF-IC instead of connecting the output end directly to a circuit block by use of wiring inside the RF-IC. Then, the output end is led to an area in proximity to the circuit block by use of wiring on a mobile terminal substrate whose resistance is low, or by use of wiring on a module whose resistance is low, thereby shortening the wiring length inside the RF-IC. This makes it possible to reduce the wiring resistance between the regulator built into the RF-IC and the circuit block, and thereby to reduce the voltage drop. As a result, the RF-IC can operate with the lower voltage of the battery. 
   The transmitter-receiver RF-IC with a built-in regulator according to the present invention can produce an effect that it is possible to reduce a minimum value of an input voltage of the regulator without increasing the area of the RF-IC, the input voltage being supplied from the battery, the RF-IC being capable of normal operation with the input voltage, whereby the operating time of a mobile terminal can be improved as compared with the prior art. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram illustrating one embodiment of a mobile terminal that uses a transmitter-receiver with a built-in regulator; 
       FIG. 2  is a diagram illustrating one embodiment of a regulator part; 
       FIG. 3  is a diagram illustrating one embodiment of a mobile terminal that uses a transmitter-receiver with a built-in regulator; 
       FIG. 4  is a diagram illustrating one embodiment of a mobile terminal that uses a transmitter-receiver with a built-in regulator; 
       FIG. 5  is a diagram illustrating one embodiment of a transmitter; 
       FIG. 6  is a diagram illustrating one embodiment of a mobile terminal that uses a transmitter-receiver with a built-in regulator; 
       FIG. 7  is a diagram illustrating a conventional example; and 
       FIG. 8  is a diagram illustrating technical problems. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments according to the present invention will be described with reference to drawings below. 
     FIG. 1  is a block diagram illustrating how the essential part of a mobile terminal compatible with GSM  850 , GSM  900 , DCS  1800  and PCS  1900  is configured according to one embodiment of the present invention. 
   As shown in  FIG. 1 , the mobile terminal according to this embodiment comprises a RF-IC  101 , a BB  102 , a PA  103 , SAWs  104   a  through  104   e , an ASW  105 , a transmitter  106   a , a receiver  107 , a RFPLL  108 , an IFPLL  109 , an antenna  111 , a regulator part  114 , and capacitors C 100  through C 102 . The regulator part  114  includes regulators  113   a  through  113   c . The SAWs  104   a ,  104   b ,  104   c  and  104   d  are receiving SAWs used for GSM  850 , GSM  900 , DCS  1800  and PCS  1900  respectively, and are used to suppress unnecessary signals. 
   The SAW  104   e  is a transmission SAW used for GSM  850 , GSM  900 , and is used to suppress unnecessary signals. 
   With the objective of generating from an input IQ signal an output signal having a desired transmit frequency, the transmitter  106   a  performs quadrature modulation and frequency conversion by use of output signals of the RFPLL  108  and of the IFPLL  109 . In addition, the transmitter  106   a  properly performs amplification, filtering, and the like. In the case of the GSM  850  or the GSM  900 , the above output signal is output to the SAW  104   e . In the case of the DCS  1800  or the PCS  1900 , the above output signal is output to the PA  103 . It is to be noted that although the output signals of the RFPLL  108  and of the IFPLL  109  are used in this embodiment, the present invention is not limited to this example. Depending on a configuration of the transmitter  106   a , only the RFPLL  108  is used in some cases. 
   With the objective of generating an output IQ signal from an input signal, the receiver  107  performs quadrature demodulation and frequency conversion by use of an output signal of the RFPLL  108 . Further, the receiver  107  properly performs amplification, filtering, and the like. In the case of the GSM  850 , the GSM  900 , the DCS  1800 , or the PCS  1900 , the above input signal is inputted from the SAW  104   a , the SAW  104   b , the SAW  104   c , or the SAW  104   d  respectively. It is to be noted that although the output signal of the RFPLL  108  is used in this embodiment, the present invention is not limited to this example. Depending on a configuration of the receiver  107 , an output signal not only of the RFPLL  108  but also of the IFPLL  109  is used in some cases. 
   The RFPLL  108  is a frequency synthesizer used to output a signal having a specified frequency. 
   The IFPLL  109  is a frequency synthesizer used to output a signal having a specified frequency. 
   The regulator  113   a  receives a voltage Vbat as an input signal and outputs a specified voltage to the PA  103 . The PA  103  uses the output voltage from the regulator  113   a  to generate a bias voltage used for, e.g., an amplifier. 
   The regulator  113   b  receives a voltage Vbat as an input signal and outputs a specified voltage. The output voltage is used as a power supply voltage for the transmitter  106   a  and the receiver  107 . 
   The regulator  113   c  receives a voltage Vbat as an input signal and outputs a specified voltage. The output voltage is used as a power supply voltage for the RFPLL  108  and the IFPLL  109 . 
   As described above, it is expected that using the dedicated regulator  113   a  to output a voltage to the PA  103  will produce an effect of reducing a possibility of deterioration in properties caused by unnecessary signals that are mixed from the PA  103  to the transmitter  106   a , the receiver  107 , the RFPLL  108 , and the IFPLL  109 . Moreover, it is also expected that using the dedicated regulator  113   c  to output a voltage to the RFPLL  108  and the IFPLL  109  will produce an effect of: reducing a possibility of deterioration in properties of the RFPLL  108  and of the IFPLL  109  caused by unnecessary signals that are mixed from the PA  103 , the transmitter  106   a , and the receiver  107 ; and decreasing the output potential of the regulator at the moment at which each of the transmitter  106   a , the receiver  107 , and the PA  103  changes its state from an OFF state to an ON state, this decrease in output potential of the regulator causing output frequencies of the RFPLL  108  and of the IFPLL  109  to change, with the result that the reconvergence time required for the output frequencies is shortened. 
   The output ends of the regulators  113   a  through  113   c  are first led out to the outside of the RF-IC  101 . Each of the output ends is then led to an area in proximity to each circuit block by use of wiring on a mobile-terminal substrate capable of reducing the wiring resistance. After that, each output end is returned to the inside of the RF-IC  101 , and is connected to each circuit block. This makes it possible to shorten the length of wiring inside the RF-IC  101 , which wiring is included in wiring from the output end of the regulator to each circuit block. To be more specific, it is possible to reduce the wiring resistance without increasing the width of the wiring inside the RF-IC  101 , and thereby to reduce the voltage drop caused by the wiring. Therefore, as compared with a case where the output end of the regulator is directly connected to each circuit block by use of the wiring inside the RF-IC  101 , it is possible to decrease a minimum value of the voltage Vbat required for the normal operation of the RF-IC  101  without causing an area of the RF-IC  101  to increase as a result of an increase in line width. As a result, it is possible to lengthen the operating time of the mobile terminal. 
   The capacitors C 100  through C 102  are used to prevent each of the regulators  113   a ,  113   b , and  113   c  from oscillating so that stable operation can be achieved. Capacitance values of the capacitors C 100  through C 102  need to be large (e.g., 1 μF). Accordingly, if the capacitors C 100  through C 102  are built into the RF-IC  101 , a large area is required, which increases the area of the RF-IC  101 , resulting in high costs. For this reason, as shown in the figure, the capacitors C 100  through C 102  are connected to the outside of the RF-IC  101 . In addition, for example, chip parts are used. 
     FIG. 2  is a diagram illustrating how the essential part of the regulator part  114  shown in  FIG. 1  is configured according to one embodiment. 
   As shown in this figure, the regulator part according to this embodiment comprises a reference-voltage generation circuit (hereinafter referred to as “BGR”), and the regulators  113   a  through  113   c . The regulator  113   a  includes an operational amplifier  201 , a PMOS transistor M 200 , and resistances R 200 , R 201 . The regulators  113   b ,  113   c  are also configured in a similar manner. Voltage Vbat is used as a supply voltage applied to the BGR  200  and to the regulators  113   a  through  113   c.    
   The BGR  200  is a circuit for generating a reference-signal voltage applied to the operational amplifier  201 . For example, a band-gap reference circuit is used as the BGR  200 . Since a common output signal from the BGR  200  is shared by the regulators  113   a  through  113   c , it is possible to reduce the circuit size. 
   In a range within which the voltage Vbat is kept sufficiently high so that properties of the BGR  200 , the operational amplifier  201 , and the PMOS transistor M 200  do not degrade, the output voltage Vo is calculated by the following equation:
 
 Vo =(1+ R 200/ R 201) Vr   (Equation 1)
 
   To be more specific, it is found out that irrespective of the voltage Vbat, the output voltage Vo is determined by Vr and the resistances R 200 ,  201 . Incidentally, although the example in which the PMOS transistor is used as M 200  is described in this embodiment, the present invention is not limited to this example. An NMOS transistor, an NPN transistor, or a PNP transistor is used in some cases. 
     FIG. 3  is a block diagram illustrating how the essential part of a mobile terminal compatible with GSM  850 , GSM  900 , DCS  1800  and PCS  1900  is configured according to another embodiment of the present invention. The embodiment shown in  FIG. 3  is different from that shown in  FIG. 1  in that a block included in reference numeral  100  is provided as a module. As is the case with the wiring on the mobile terminal, the wiring resistance of wiring on the module can be reduced. Therefore, it is possible to produce the same effects as those in the embodiment shown in  FIG. 1 . 
     FIG. 4  is a block diagram illustrating how the essential part of a mobile terminal compatible with GSM  850 , GSM  900 , DCS  1800 , PCS  1900  is configured according to another embodiment of the present invention. The embodiment shown in  FIG. 4  is different from that shown in  FIG. 3  in that a regulator  113   d  is added to the regulator part  114 , and in that two regulators  113   b ,  113   d  supply the supply voltage to the transmitter  106   a  in the embodiment shown in  FIG. 4 , whereas only the regulator  113   b  supplies the supply voltage to the transmitter  106   a  in the embodiment shown in  FIG. 3 . In addition, the transmitter  106   b  is a transmitter that supports, as modulated signals, both the GMSK (Gaussian minimum shift keying) modulation and the 8PSK modulation used for the EDGE (Enhanced data for global evolution) specifications. The transmitter  106   b  includes: a PM circuit block  300  which is used only for transmission of phase information of a modulated signal; an AM circuit block  301  which is used for transmission of amplitude information or for transmission of both the amplitude information and the phase information. 
   The regulator  113   b  supplies the supply voltage to the PM circuit block  300 , and the regulator  113   d  supplies the supply voltage to the AM circuit block  301 . Thus, by using the respective different regulators to supply the supply voltages to the PM circuit block  300  and the AM circuit block  301 , it is possible to suppress unnecessary interaction of the phase information with the amplitude information, and accordingly it is expected that the deterioration in properties of the transmitter  106   b  will be reduced. 
   Incidentally, what is important in this embodiment is that, as described above, the respective different regulators are used to supply the supply voltages to the PM circuit block  300  and the AM circuit block  301 . Therefore, it is not always necessary to configure the mobile terminal exactly as shown in  FIG. 4 . For example, the regulator  113   d  supplies the supply voltage to the PM circuit block  300 , whereas the regulator  113   b  supplies the supply voltage to the AM circuit block  301 . 
     FIG. 5  is a block diagram illustrating how the essential part of the transmitter  106   b  shown in  FIG. 4  is configured according to one embodiment. The transmitter  106   b  comprises: a quadrature modulator (hereinafter referred to as “MOD”)  400 ; a phase comparator (hereinafter referred to as “PD”)  401 ; a filter  402 ; a TXVCO  403 ; variable-gain amplifiers (hereinafter referred to as “VGA”)  404   a ,  404   b ; a mixer  405 ; an envelope comparator (hereinafter referred to as “AMD”)  406 ; a filter  407 ; a voltage-to-current converter (hereinafter referred to as “VIC”)  408 ; a filter  409 ; and a buffer amplifier (hereinafter referred to as “DRV”)  410 . The filter  402  includes capacitors C 400 , C 401 , and a resistor R 400 . The filter  407  includes capacitors C 402 ,  403 , and a resistor R 401 . The filter  409  includes a capacitor C 404 . 
   The PM circuit block  300  shown in  FIG. 4  includes the PD  401 , and the TXVCO  403 . The AM circuit block  301  shown in  FIG. 4  includes the MOD  400 , the VGAs  404   a ,  404   b , the AMD  406 , the VIC  408 , the DRV  410 , and the MIX  405 . 
   The MOD  400  performs quadrature modulation of an inputted IQ signal by use of an output signal from the IFPLL  109 . 
   The PD  401  outputs an electric current whose value is in proportion to the phase difference between two input signals. 
   The filter  402  suppresses unnecessary signals included in the output signal of the PD  401 . 
   The TXVCO  403  is a voltage-controlled oscillator for outputting a signal whose frequency is determined by the output-signal voltage of the filter  402 . 
   The VGA  404   a  is a variable-gain amplifier whose gain is determined by a first control voltage. 
   The mixer  405  down-converts a frequency of an input signal by use of an output signal of the RFPLL  108 . 
   The AMD  406  outputs an electric current whose value is in proportional to the difference in envelope voltage between two input signals. 
   The filter  407  suppresses unnecessary signals included in the output signal of the ADM  406 . 
   The VIC  408  converts the input voltage into an current signal. 
   The filter  409  suppresses unnecessary signals included in the output signal of the VIC  408 . 
   The DRV  410  provides the input voltage with a specified gain. The output voltage becomes the first control voltage of the VGA  404   a.    
   The VGA  404   b  is a variable-gain amplifier whose gain is determined by a second control voltage. 
   The PD  401 , the filter  402 , the TXVCO  403 , the VGA  404   a , and the MIX  405  form a phase-locked loop in which a phase of an output signal of the MOD  400  is used as a reference signal. As a result, the output signal phase of the MOD  400  is obtained at the output of the VGA  404   a . In addition, a frequency of an output signal of the VGA  404   a  becomes a difference frequency between a frequency of an output signal of the RFPLL  108  and a frequency of an output signal of the MOD  400 . 
   The AMD  406 , the filter  407 , the VIC  408 , the filter  409 , the DRV  410 , the VGA  404   a , and the MIX  405  form an envelope-locked loop in which an envelope of an output signal of the MOD  400  is used as a reference signal. As a result, the output signal envelope of the MOD  400  is obtained at the output of the VGA  404   a.    
   Since the phase-locked loop and the envelope-locked loop work as described above, the phase and envelope of the output signal of the MOD  400  are obtained by the output signal of the VGA  404   a  in the end, and the frequency thereof is determined by the output frequency of the IFPLL  109  and that of the RFPLL  108 . In other words, the transmitter according to this embodiment can perform frequency conversion while storing inputted modulation information. 
     FIG. 6  is a block diagram illustrating how the essential part of a mobile terminal compatible with GSM  850 , GSM  900 , DCS  1800  and PCS  1900  are configured according to another embodiment of the present invention. The embodiment shown in  FIG. 6  is different from that shown in  FIG. 3  in that it is not necessary to supply the supply voltage from the RF-IC  101  to the PA  103 . Therefore, it becomes unnecessary to use the regulator  113   a  and the capacitor C 100  shown in  FIG. 3 . The PA  103  generates all required voltage signals from the voltage Vbat. 
   Incidentally, although the above embodiment has been described using the example compatible with GSM  850 , GSM  900 , DCS  1800 , and PCS  1900 , needless to say, the present invention is not limited to this example. For example, there is also a case where only GSM  900  is used, or a case where GSM  900  and DCS  1800  are used in combination. Further, there is also a case where other applications (for example, W-CDMA) are used. Moreover, there is also a case where the SAW  104   e  is not used. 
   Incidentally, the reference numerals used in the diagrams of the present application will be listed below.
       100  . . . Module     101  . . . Transmitter-receiver     102  . . . Base band     103  . . . Power amplifier     104  . . . SAW filter     105  . . . Antenna switch     106  . . . Transmitter     107  . . . Receiver     108  . . . RFPLL     109  . . . IFPLL     111  . . . Antenna     113  . . . Regulator     114  . . . Regulator part     200  . . . Reference-voltage generation circuit     201  . . . Operational amplifier     300  . . . PM circuit block     301  . . . AM circuit block     400  . . . Quadrature modulator     401  . . . Phase comparator     402 ,  407 ,  409  . . . Filters     403  . . . TXVCO     404  . . . Variable-gain amplifier     405  . . . Mixer     406  . . . Envelope comparator     408  . . . Voltage-to-current converter     410  . . . Buffer amplifier