PATENT DOCUMENT

Publication Number: US-8255009-B2
Application Number: US-11026008-A
Country: US
Kind Code: B2

Title: Radio frequency communications circuitry with power supply voltage and gain control

Abstract:
Portable electronic devices are provided with wireless circuitry. The wireless circuitry may include one or more sets of radio-frequency power amplifiers. The radio-frequency power amplifiers are used to amplify radio-frequency signals that are transmitted by the portable electronic devices. Each power amplifier may have multiple gain mode settings. Gain stages within the power amplifiers may be selectively enabled in accordance with the gain mode settings. When a higher level of gain is required, all of the gain stages may be enabled. When a lower level of gain is required, some of the gain stages may be disabled to conserve power. An adjustable power supply may be used to provide an adjustable power supply voltage to the power amplifiers. The adjustable power supply voltage can be reduced when it is desired to minimize power consumption at a particular gain mode setting. Gain mode and power supply settings may be adjusted simultaneously.

Claims:
1. Wireless communications circuitry on a portable electronic device wherein the wireless communications circuitry operates using power from a battery, the wireless communications circuitry comprising:
 at least one radio-frequency power amplifier that amplifies radio-frequency signals that are transmitted from the portable electronic device; 
 at least one additional radio-frequency power amplifier that receives power directly from the battery; and 
 adjustable power supply circuitry that supplies an adjustable power supply voltage to the radio-frequency power amplifier. 
 
     
     
       2. The wireless communications circuitry defined in  claim 1  further comprising:
 a battery input in the adjustable power supply circuitry that receives a battery voltage from the battery; and 
 a power supply voltage output at which the adjustable power supply voltage is supplied to the radio-frequency power amplifier, wherein the adjustable power supply voltage is less than the battery voltage. 
 
     
     
       3. The wireless communications circuitry defined in  claim 2  wherein the adjustable power supply circuitry comprises a dc-to-dc converter. 
     
     
       4. The wireless communications circuitry defined in  claim 1  wherein the radio-frequecy power amplifier comprises at least one adjustable gain mode radio-frequency power amplifier that amplifies the radio-frequency signals that are transmitted from the portable electronic device in accordance with a gain mode level setting, the wireless communications circuitry further comprising baseband processor circuitry that generates control signals that adjust the gain mode level setting of the radio-frequency power amplifier. 
     
     
       5. The wireless communications circuitry defined in  claim 1  wherein the radio-frequency power amplifier comprises a plurality of gain stages that are selectively enabled to adjust a gain mode level setting, wherein the plurality of gain stages are selectively enabled to adjust the gain mode level setting between at least a first gain setting and a second gain setting, and wherein the first gain setting is larger than the second gain setting. 
     
     
       6. The wireless communications circuitry defined in  claim 5  further comprising a baseband processor integrated circuit that generates control signals that adjust the gain mode level setting of the radio-frequency power amplifier. 
     
     
       7. The wireless communications circuitry defined in  claim 6  wherein the adjustable power supply circuitry comprises a dc-to-dc converter. 
     
     
       8. The wireless communications circuitry defined in  claim 1  wherein the radio-frequency power amplifier comprises at least one adjustable gain mode radio-frequency power amplifier that amplifies the radio-frequecy signals that are transmitted from the portable electronic device in accordance with a gain mode level setting, the wireless communications circuitry further comprising a baseband processor integrated circuit that generates control signals that adjust the gain mode level setting of the radio-frequency power amplifier. 
     
     
       9. The wireless communications circuitry defined in  claim 8  wherein the adjustable power supply circuitry comprises a dc-to-dc converter. 
     
     
       10. The wireless communications circuitry defined in  claim 1  wherein the radio-frequency power amplifier comprises a plurality of gain stages that are selectively enabled to adjust a gain mode level setting, wherein the plurality of gain stages are selectively enabled to adjust the gain mode level setting between at least a first gain setting and a second gain setting, wherein the first gain setting is larger than the second gain setting, wherein a first number of the plurality of gain stages are selectively enabled to adjust the gain mode level setting to the first gain setting, wherein a second number of the plurality of gain stages are selectively enabled to adjust the gain mode level setting to the second gain setting, and wherein the first number of the plurality of gain stages is greater than the second number of the plurality of gain stages. 
     
     
       11. The wireless communications circuitry defined in  claim 1  wherein the radio-frequency power amplifier comprises a plurality of gain stages that are selectively enabled to adjust a gain mode level setting, wherein the plurality of gain stages are selectively enabled to adjust the gain mode level setting between at least a first gain setting and a second gain setting, wherein the first gain setting is larger than the second gain setting, wherein at least a given one of the plurality of gain stages is selectively enabled to adjust the gain mode level setting to the first gain setting, wherein at least the given one of the plurality of gain stages is selectively disabled to adjust the gain mode level setting to the second gain setting. 
     
     
       12. A method for operating portable electronic device wireless communications circuitry having a radio-frequency power amplifier with multiple gain modes, an adjustable power supply, and an additional radio-frequency power amplifier, the method comprising:
 applying control signals to the radio-frequency power amplifier to place the radio-frequency power amplifier in a selected one of the multiple gain modes; 
 with the adjustable power supply, providing an adjustable power supply voltage to the radio-frequency power amplifier; and 
 with the additional radio-frequency power amplifier, receiving a battery voltage directly from a battery. 
 
     
     
       13. The method defined in  claim 12 , wherein the control signals comprise gain mode level control signals, wherein applying the control signals comprises:
 with a baseband processor integrated circuit, generating the gain mode level control signals. 
 
     
     
       14. The method defined in  claim 13  further comprising:
 reducing the adjustable power supply voltage while maintaining the radio-frequency power amplifier in a given one of the gain modes to conserve power. 
 
     
     
       15. The method defined in  claim 12  wherein the wireless communications circuitry is part of a portable electronic device that communicates with wireless network equipment, the method further comprising:
 receiving transmit power control commands from the network equipment with the wireless communications circuitry; and 
 in accordance with the received transmit power control commands, simultaneously adjusting both the gain mode of the radio-frequency power amplifier and the power supply voltage produced by the adjustable power supply to minimize power consumption. 
 
     
     
       16. The method defined in  claim 15  wherein adjusting the power supply voltage produced by the adjustable power supply comprises adjusting an output voltage produced by a dc-to-dc converter. 
     
     
       17. The method defined in  claim 12  wherein applying the control signals comprises:
 applying at least a first control signal to place the radio-frequency power amplifier in a first gain mode, wherein the first control signal selectively enables at least a given portion of the radio-frequency power amplifier; and 
 applying at least a second control signal to place the radio-frequency power amplifier in a second gain mode that is less than the first gain mode, wherein the second control signal selectively disables at least the given portion of the radio-frequency power amplifier. 
 
     
     
       18. A portable electronic device that is powered by a battery, comprising:
 an adjustable power supply that receives a battery voltage from the battery and that produces a corresponding adjustable power supply voltage; 
 antenna structures; 
 a first set of radio-frequency power amplifiers that receive power directly from the battery; and 
 a second set of radio-frequency power amplifiers that amplify radio-frequency signals that are transmitted through the antenna structures, wherein the second set of radio-frequency power amplifiers are powered by the adjustable power supply voltage and are responsive to gain mode control commands. 
 
     
     
       19. The portable electronic device defined in  claim 18  further comprising:
 a baseband processor integrated circuit that supplies the gain mode control commands to the second set of radio-frequency power amplifiers to adjust each of the second set of radio-frequency power amplifiers to selectively operate in high gain and low gain modes. 
 
     
     
       20. The portable electronic device defined in  claim 19  wherein the adjustable power supply comprises a dc-to-dc converter that supplies at least a first power supply voltage and a second power supply voltage, wherein the first power supply voltage is less than the second power supply voltage. 
     
     
       21. The portable electronic device defined in  claim 18  further comprising a transceiver circuit that receives transmit power commands through the antenna structures, wherein the second set of radio-frequency power amplifiers are responsive to gain mode control commands and wherein the adjustable power supply voltage and gain mode control commands are generated in real time to adjust power amplifier power consumption in accordance with the transmit power commands.

Description:
BACKGROUND 
     This invention relates generally to wireless communications circuitry, and more particularly, to wireless communications circuitry with power management capabilities. 
     Handheld electronic devices and other portable electronic devices are becoming increasingly popular. Examples of handheld devices include handheld computers, cellular telephones, media players, and hybrid devices that include the functionality of multiple devices of this type. Popular portable electronic devices that are somewhat larger than traditional handheld electronic devices include laptop computers and tablet computers. 
     Due in part to their mobile nature, portable electronic devices are often provided with wireless communications capabilities. For example, handheld electronic devices may use long-range wireless communications to communicate with wireless base stations. Cellular telephones and other devices with cellular capabilities may communicate using cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz. Portable electronic devices may also use short-range wireless communications links. For example, portable electronic devices may communicate using the Wi-Fi® (IEEE 802.11) bands at 2.4 GHz and 5.0 GHz and the Bluetooth® band at 2.4 GHz. Communications are also possible in data service bands such as the 3G data communications band at 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System band). The use of 3G communications schemes for supporting voice communications is also possible. 
     To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to reduce the size of components that are used in these devices. For example, manufacturers have made attempts to miniaturize the batteries used in handheld electronic devices. 
     An electronic device with a small battery has limited battery capacity. Unless care is taken to consume power wisely, an electronic device with a small battery may exhibit unacceptably short battery life. Techniques for reducing power consumption may be particularly important in wireless devices that support cellular telephone communications, because users of cellular telephone devices often demand long “talk” times. 
     It would therefore be desirable to be able to provide wireless communications circuitry with improved power management capabilities. 
     SUMMARY 
     A portable electronic device such as a handheld electronic device is provided with wireless communications circuitry that includes power management capabilities. The wireless communications circuitry may include a radio-frequency transceiver and antenna structures. Power amplifiers may be provided to amplify radio-frequency signals from the transceiver before they are transmitted from the portable electronic device using the antenna structures. 
     The portable electronic device may be powered by a battery. The battery voltage may vary as a function of time. For example, as the battery becomes depleted, the battery voltage may drop. As a result, the battery voltage at the beginning of its life may be excessive. To avoid unnecessarily high levels of power consumption by the power amplifier circuitry at the beginning of the battery&#39;s life when the battery voltage is elevated, power supply circuitry may be used to regulate the power supply voltage that is supplied to the power amplifiers. 
     The power amplifiers may contain multiple selectively enabled gain stages. When it is desired to operate in a high gain mode, the gain stages may all be enabled. When it not necessary to produce large output powers, power consumption by the power amplifiers can be reduced by placing the power amplifiers in one or more lower gain modes of operation. During the lower gain modes of operation, one or more of the gain stages are selectively disabled. 
     The power supply voltage that is provided to the power amplifier may be adjusted in real time to accommodate desired power amplifier output power requirements while minimizing power consumption. Both power supply voltage adjustments and gain mode adjustments may be made simultaneously to optimize performance. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in which wireless communications circuitry with power management capabilities may be used in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative portable electronic device in accordance with an embodiment of the present invention. 
         FIG. 3  is a circuit diagram of illustrative wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 4  is a circuit diagram of illustrative components that may be used in wireless communications circuitry with power management capabilities in accordance with an embodiment of the present invention. 
         FIG. 5  is a graph showing how battery voltage may decrease with time and how the output of a voltage regulator such as a dc-to-dc converter may be adjusted in accordance with an embodiment of the present invention. 
         FIG. 6  is a graph showing how the amount of current consumed by a radio-frequency power amplifier in wireless communications circuitry may be adjusted by adjusting the gain setting and power supply voltage for the radio-frequency power amplifier in accordance with an embodiment of the present invention. 
         FIG. 7  is a graph showing how an adjustable power supply circuit such as an adjustable dc-to-dc converter may provide a radio-frequency power amplifier with different power supply voltages and how different power amplifier gain settings may be used when supplying various amounts of radio-frequency output power in accordance with an embodiment of the present invention. 
         FIG. 8  is a graph showing how power amplifier efficiency may be greatest at relatively large power supply voltages in electronic devices using wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 9  is a graph showing how power amplifier efficiency may be greatest at relatively large operating currents in electronic devices using wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 10  is a graph showing how power amplifier power supply voltage may be adjusted as a function of various required radio-frequency power requirements in accordance with an embodiment of the present invention. 
         FIG. 11  is a graph showing how power amplifier gain settings and power supply voltages may be adjusted to accommodate various different transmitted radio-frequency power requirements in accordance with an embodiment of the present invention. 
         FIG. 12  is a flow chart of illustrative steps involved in using radio-frequency power amplifier gain and power supply voltage adjustments in managing power consumption in wireless communications circuitry for a portable electronic device in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates generally to wireless communications, and more particularly, to managing power consumption by wireless communications circuitry in wireless electronic devices. 
     The wireless electronic devices may be portable electronic devices such as laptop computers or small portable computers of the type that are sometimes referred to as ultraportables. Portable electronic devices may also be somewhat smaller devices. Examples of smaller portable electronic devices include wrist-watch devices, pendant devices, headphone and earpiece devices, and other wearable and miniature devices. With one suitable arrangement, the portable electronic devices may be handheld electronic devices. 
     The wireless electronic devices may be, for example, cellular telephones, media players with wireless communications capabilities, handheld computers (also sometimes called personal digital assistants), remote controllers, global positioning system (GPS) devices, and handheld gaming devices. The wireless electronic devices may also be hybrid devices that combine the functionality of multiple conventional devices. Examples of hybrid portable electronic devices include a cellular telephone that includes media player functionality, a gaming device that includes a wireless communications capability, a cellular telephone that includes game and email functions, and a portable device that receives email, supports mobile telephone calls, has music player functionality and supports web browsing. These are merely illustrative examples. 
     An illustrative portable electronic device in accordance with an embodiment of the present invention is shown in  FIG. 1 . Device  10  of  FIG. 1  may be, for example, a handheld electronic device. 
     Device  10  may have housing  12 . Antennas for handling wireless communications may be housed within housing  12  (as an example). 
     Housing  12 , which is sometimes referred to as a case, may be formed of any suitable materials including, plastic, glass, ceramics, metal, or other suitable materials, or a combination of these materials. In some situations, housing  12  or portions of housing  12  may be formed from a dielectric or other low-conductivity material, so that the operation of conductive antenna elements that are located in proximity to housing  12  is not disrupted. Housing  12  or portions of housing  12  may also be formed from conductive materials such as metal. An illustrative housing material that may be used is anodized aluminum. Aluminum is relatively light in weight and, when anodized, has an attractive insulating and scratch-resistant surface. If desired, other metals can be used for the housing of device  10 , such as stainless steel, magnesium, titanium, alloys of these metals and other metals, etc. In scenarios in which housing  12  is formed from metal elements, one or more of the metal elements may be used as part of the antennas in device  10 . For example, metal portions of housing  12  may be shorted to an internal ground plane in device  10  to create a larger ground plane element for that device  10 . To facilitate electrical contact between an anodized aluminum housing and other metal components in device  10 , portions of the anodized surface layer of the anodized aluminum housing may be selectively removed during the manufacturing process (e.g., by laser etching). 
     Housing  12  may have a bezel  14 . The bezel  14  may be formed from a conductive material and may serve to hold a display or other device with a planar surface in place on device  10 . As shown in  FIG. 1 , for example, bezel  14  may be used to hold display  16  in place by attaching display  16  to housing  12 . 
     Display  16  may be a liquid crystal diode (LCD) display, an organic light emitting diode (OLED) display, or any other suitable display. The outermost surface of display  16  may be formed from one or more plastic or glass layers. If desired, touch screen functionality may be integrated into display  16  or may be provided using a separate touch pad device. An advantage of integrating a touch screen into display  16  to make display  16  touch sensitive is that this type of arrangement can save space and reduce visual clutter. 
     Display screen  16  (e.g., a touch screen) is merely one example of an input-output device that may be used with electronic device  10 . If desired, electronic device  10  may have other input-output devices. For example, electronic device  10  may have user input control devices such as button  19 , and input-output components such as port  20  and one or more input-output jacks (e.g., for audio and/or video). Button  19  may be, for example, a menu button. Port  20  may contain a 30-pin data connector (as an example). Openings  24  and  22  may, if desired, form microphone and speaker ports. In the example of  FIG. 1 , display screen  16  is shown as being mounted on the front face of handheld electronic device  10 , but display screen  16  may, if desired, be mounted on the rear face of handheld electronic device  10 , on a side of device  10 , on a flip-up portion of device  10  that is attached to a main body portion of device  10  by a hinge (for example), or using any other suitable mounting arrangement. 
     A user of electronic device  10  may supply input commands using user input interface devices such as button  19  and touch screen  16 . Suitable user input interface devices for electronic device  10  include buttons (e.g., alphanumeric keys, power on-off, power-on, power-off, and other specialized buttons, etc.), a touch pad, pointing stick, or other cursor control device, a microphone for supplying voice commands, or any other suitable interface for controlling device  10 . Although shown schematically as being formed on the top face of electronic device  10  in the example of  FIG. 1 , buttons such as button  19  and other user input interface devices may generally be formed on any suitable portion of electronic device  10 . For example, a button such as button  19  or other user interface control may be formed on the side of electronic device  10 . Buttons and other user interface controls can also be located on the top face, rear face, or other portion of device  10 . If desired, device  10  can be controlled remotely (e.g., using an infrared remote control, a radio-frequency remote control such as a Bluetooth remote control, etc.). 
     Electronic device  10  may have ports such as port  20 . Port  20 , which may sometimes be referred to as a dock connector, 30-pin data port connector, input-output port, or bus connector, may be used as an input-output port (e.g., when connecting device  10  to a mating dock connected to a computer or other electronic device). Device  10  may also have audio and video jacks that allow device  10  to interface with external components. Typical ports include power jacks to recharge a battery within device  10  or to operate device  10  from a direct current (DC) power supply, data ports to exchange data with external components such as a personal computer or peripheral, audio-visual jacks to drive headphones, a monitor, or other external audio-video equipment, a subscriber identity module (SIM) card port to authorize cellular telephone service, a memory card slot, etc. The functions of some or all of these devices and the internal circuitry of electronic device  10  can be controlled using input interface devices such as touch screen display  16 . 
     Components such as display  16  and other user input interface devices may cover most of the available surface area on the front face of device  10  (as shown in the example of  FIG. 1 ) or may occupy only a small portion of the front face of device  10 . Because electronic components such as display  16  often contain large amounts of metal (e.g., as radio-frequency shielding), the location of these components relative to the antenna elements in device  10  should generally be taken into consideration. Suitably chosen locations for the antenna elements and electronic components of the device will allow the antennas of electronic device  10  to function properly without being disrupted by the electronic components. 
     Examples of locations in which antenna structures may be located in device  10  include region  18  and region  21 . These are merely illustrative examples. Any suitable portion of device  10  may be used to house antenna structures for device  10  if desired. 
     If desired, electronic device  10  may be a portable electronic device such as a laptop or other portable computer. For example, electronic device  10  may be an ultraportable computer, a tablet computer, or other suitable portable computing device. Electronic device  10  may also be a handheld device. Power management considerations are particularly important in small devices such as handheld devices, because space is at a premium in small devices which limits that amount of space available for batteries. 
     A schematic diagram of an embodiment of an illustrative portable electronic device such as a handheld electronic device is shown in  FIG. 2 . Portable device  10  may be a mobile telephone, a mobile telephone with media player capabilities, a handheld computer, a remote control, a game player, a global positioning system (GPS) device, a laptop computer, a tablet computer, an ultraportable computer, a combination of such devices, or any other suitable portable electronic device. 
     As shown in  FIG. 2 , device  10  may include storage  34 . Storage  34  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory), volatile memory (e.g., battery-based static or dynamic random-access-memory), etc. 
     Processing circuitry  36  may be used to control the operation of device  10 . Processing circuitry  36  may be based on a processor such as a microprocessor and other suitable integrated circuits. With one suitable arrangement, processing circuitry  36  and storage  34  are used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. Processing circuitry  36  and storage  34  may be used in implementing suitable communications protocols. Communications protocols that may be implemented using processing circuitry  36  and storage  34  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, protocols for handling 3G data services such as UMTS, cellular telephone communications protocols, etc. 
     To minimize power consumption, processing circuitry  36  or other suitable control circuitry on device  10  may be used in implementing power management functions. For example, processing circuitry  36  may be used to adjust the gain of radio-frequency power amplifier circuitry on device  10  and may be used to adjust the power supply voltages that are used in powering the radio-frequency power amplifier circuitry. These adjustments may be made automatically in real time. For example, processing circuitry  36  may be used to implement a control scheme in which the power amplifier circuitry is adjusted to accommodate transmission power level requests received from a wireless network. 
     Input-output devices  38  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Display screen  16 , button  19 , microphone port  24 , speaker port  22 , and dock connector port  20  are examples of input-output devices  38 . 
     Input-output devices  38  can include user input-output devices  40  such as buttons, touch screens, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, etc. A user can control the operation of device  10  by supplying commands through user input devices  40 . Display and audio devices  42  may include liquid-crystal display (LCD) screens or other screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices  42  may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices  42  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
     Wireless communications devices  44  may include communications circuitry such as radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry (e.g., power amplifier circuitry that is controlled by control signals from processing circuitry  36  to minimize power consumption), passive RF components, antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Device  10  can communicate with external devices such as accessories  46 , computing equipment  48 , and wireless network  49  as shown by paths  50  and  51 . Paths  50  may include wired and wireless paths. Path  51  may be a wireless path. Accessories  46  may include headphones (e.g., a wireless cellular headset or audio headphones) and audio-video equipment (e.g., wireless speakers, a game controller, or other equipment that receives and plays audio and video content), a peripheral such as a wireless printer or camera, etc. 
     Computing equipment  48  may be any suitable computer. With one suitable arrangement, computing equipment  48  is a computer that has an associated wireless access point (router) or an internal or external wireless card that establishes a wireless connection with device  10 . The computer may be a server (e.g., an internet server), a local area network computer with or without internet access, a user&#39;s own personal computer, a peer device (e.g., another portable electronic device  10 ), or any other suitable computing equipment. 
     Wireless network  49  may include any suitable network equipment, such as cellular telephone base stations, cellular towers, wireless data networks, computers associated with wireless networks, etc. For example, wireless network  49  may include network management equipment that monitors the wireless signal strength of the wireless handsets (cellular telephones, handheld computing devices, etc.) that are in communication with network  49 . 
     To improve the overall performance of the network and to ensure that interference between handsets is minimized, the network management equipment may send power adjustment commands (sometimes referred to as transmit power control commands) to each handset. The transmit power control settings that are provided to the handsets direct handsets with weak signals to increase their transmit powers, so that their signals will be properly received by the network. At the same time, the transmit power control settings may instruct handsets whose signals are being received clearly at high power to reduce their transmit power control settings. This reduces interference between handsets and allows the network to maximize its use of available wireless bandwidth. 
     When devices such as device  10  receive transmit power control settings from the network, each device  10  may make suitable transmission power adjustments. For example, a device  10  may adjust the radio-frequency power amplifiers that are used to amplify the radio-frequency signals that are being transmitted by device  10 . These adjustments may include gain mode settings adjustments and power supply voltage adjustments. Gain mode adjustments control the gain setting of the power amplifier. For example, a gain mode adjustment may control whether a power amplifier is operating in a high gain mode in which all power amplifier stages that are available are being used or a low gain mode in which one or more of the gain stages on the power amplifier have been shut down to conserve power. Power supply voltage adjustments may be used to help minimize power consumption at a given gain setting. 
     The antenna structures and wireless communications devices of device  10  may support communications over any suitable wireless communications bands. For example, wireless communications devices  44  may be used to cover communications frequency bands such as cellular telephone voice and data bands at 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and the communications band data at 2170 MHz band (commonly referred to as a UMTS or Universal Mobile Telecommunications System band), the Wi-Fi® (IEEE 802.11) bands at 2.4 GHz and 5.0 GHz (also sometimes referred to as wireless local area network or WLAN bands), the Bluetooth® band at 2.4 GHz, and the global positioning system (GPS) band at 1550 MHz. 
     Device  10  can cover these communications bands and/or other suitable communications bands with proper configuration of the antenna structures in wireless communications circuitry  44 . Any suitable antenna structures may be used in device  10 . For example, device  10  may have one antenna or may have multiple antennas. The antennas in device  10  may each be used to cover a single communications band or each antenna may cover multiple communications bands. If desired, one or more antennas may cover a single band while one or more additional antennas are each used to cover multiple bands. These are merely illustrative arrangements. Any suitable antenna structures may be used in device  10  if desired. 
     Illustrative wireless communications devices  44  that may be used in device  10  are shown in  FIG. 3 . As shown in  FIG. 3 , wireless communications devices  44  may include one or more antennas such as antennas  62 . Data signals that are to be transmitted by device  10  may be provided to baseband module  52  (e.g., from processing circuitry  36  of  FIG. 2 ). Baseband module  52  may be implemented using a single integrated circuit (e.g., a baseband processor integrated circuit) or using multiple circuits. Baseband module  52  may provide data to be transmitted to transmitter circuitry within transceiver circuits  54 . The transmitter circuitry may be coupled to power amplifier circuitry  56  via path  55 . 
     During data transmission, power amplifier circuitry  56  may boost the output power of transmitted signals to a sufficiently high level to ensure adequate signal transmission. Radio-frequency (RF) output stage circuitry  57  may contain radio-frequency switches and passive elements such as duplexers and diplexers. The switches in RF output stage circuitry  57  may, if desired, be used to switch devices  44  between a transmitting mode and a receiving mode. Duplexer and diplexer circuits and other passive components in RF output stage may be used to route input and output signals based on their frequency. 
     Matching circuitry  60  may include a network of passive components such as resistors, inductors, and capacitors and ensures that antenna structures  62  are impedance matched to the rest of the circuitry  44 . Wireless signals that are received by antenna structures  62  may be passed to receiver circuitry in transceiver circuitry  54  over a path such as path  64 . 
     Each power amplifier (e.g., each power amplifier in power amplifiers  56 ) may include one or more power amplifier stages such as stages  70 . As an example, each power amplifier may be used to handle a separate communications band and each such power amplifier may have three series-connected power amplifier stages  70 . Stages  70  may have control inputs such as inputs  72  that receive control signals. The control signals may be provided using a control signal path such as path  76 . In a typical scenario, processing circuitry  36  ( FIG. 2 ) may provide control signals to stages  70  using a path such as path  76  and paths such as paths  72 . The control signals from processing circuitry  36  may be used to selectively enable and disable stages  70 . 
     By enabling and disabling stages  70  selectively, the power amplifier may be placed into different gain modes. For example, the power amplifier may be placed into a high gain mode by enabling all three of power amplifier stages  70  or may be placed into a low gain mode by enabling two of the power amplifier stages. Other configurations may be used if desired. For example, a very low gain mode may be supported by turning on only one of three gain stages or arrangements with more than three gain mode settings may be provided by selectively enabling other combinations of gain stages (e.g., in power amplifiers with three or more than three gains stages). 
     Adjustable power supply circuitry such as adjustable power supply circuitry  78  may be powered by battery  83 . Battery  83  may supply a positive battery voltage to adjustable power supply circuitry  78  at positive power supply terminal  82  and may supply a ground voltage to adjustable power supply circuitry  78  at ground power supply terminal  84 . Battery  83  may be a lithium ion battery, a lithium polymer battery, or a battery of any other suitable type. 
     Initially, the voltage supplied by battery  83  may be high. As battery  83  becomes depleted, the voltage supplied by battery  83  will tend to drop. By using adjustable power supply circuitry  78 , the amount of voltage Vcc that is supplied to power amplifier circuitry  56  over power supply voltage path  86  may be maintained at a relatively constant value. This helps to avoid wasteful situations in which the circuitry of power amplifiers  56  is supplied with excessive voltages while battery  83  is fresh. Such excessive voltages may lead to undesirably large power consumption by circuitry  56 . 
     Adjustable power supply circuitry  78  may be controlled by control signals received over a path such as path  80 . The control signals may be provided to adjustable power supply circuitry  78  from processing circuitry  36  ( FIG. 2 ) or any other suitable control circuitry. The control signals on path  80  may be used to adjust the magnitude of the positive power supply voltage Vcc that is provided to power amplifier circuitry  56  over path  86 . These power supply voltage adjustments may be made at the same time as gain mode adjustments are being made to the power amplifier circuitry  56 . By making both power supply voltage adjustments and gain level adjustments to power amplifier circuitry  56 , power consumption by power amplifier circuitry  56  can be minimized and battery life may be extended under a variety of operating conditions. 
     Consider, as an example, a situation in which device  10  has received a transmit power command from a wireless base station that specifies a desired radio-frequency power to be transmitted by device  10 . Processor  36  or other suitable processing circuitry on device  10  can determine appropriate settings for the gain level of power amplifier circuitry  56  and for the power supply voltage Vcc that is supplied to power amplifier circuitry  56 . Control signals from processing circuitry  36  may be supplied power amplifier circuitry on path  76  that adjust the gain level of the power amplifier (e.g., by turning on and off certain gain stages  70  in power amplifier circuitry  56 ). Additional adjustments to the performance of the power amplifier circuitry may be made by using path  86  to supply a desired adjustable power supply voltage Vcc to power amplifier circuitry  56  from adjustable power supply circuitry  78  in accordance with control signals supplied on path  80 . During these adjustments, the processing circuitry can take care to satisfy desired operating constraints on power amplifier circuitry  56  such as minimum desired output power settings and minimum values of adjacent channel leakage ratio (the ratio of transmitted power to adjacent channel power). 
     Wireless communications devices  44  may include circuitry for supporting any suitable types of wireless communications. For example, devices  44  may include circuitry for supporting traditional cellular telephone and data communications (sometimes referred to as “2G” communications). An example of 2G cellular telephone systems are those based on the Global System for Mobile Communication (GSM) systems. Devices  44  may also include circuitry for supporting newer communications formats (sometimes referred to as “3G” communications). These newer formats may support increased communications speeds and may be used for both data and voice traffic. Such formats may use wide band code-division multiple access (CDMA) technology. 
     Illustrative wireless communications devices  44  that may be used when it is desired to support both 2G and 3G wireless communications in the same portable electronic device are shown in  FIG. 4 . 
     In the illustrative arrangement of  FIG. 4 , radio-frequency signals are received and transmitted using antenna  62 . Switch circuitry  88  may be used to selectively connect either test path  92  or antenna path  90  to path  94 . During testing and calibration operations, path  92  may be connected to path  94 . During normal operation, lines  94  and  90  are electrically connected to each other, so that antenna signals are routed between antenna  62  and filter circuitry  60 . Filter circuitry  60  may include any suitable active and/or passive filter components, such as surface acoustic wave (SAW) devices, inductors, capacitors, resistors, etc. Filter circuitry  60  may be used, for example, to reject out-of-band signals. 
     When it is desired to use devices  44  to communicate over a 2G link, radio-frequency signals may be transmitted and received though circuit block  56 ′. Circuitry  56 ′ may include power amplifiers that are used to amplify transmitted radio-frequency signals. Illustrative bands that may be handled using block  56 ′ include 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz (2170 MHz). 
     When it is desired to use devices  44  to communicate over a 3G link, radio-frequency signals may be transmitted and received through power amplifiers  56 . Power amplifiers  56  may have associated baluns for impedance matching and duplexer circuitry that separates received and transmitted signals. Received signals may be conveyed from power amplifiers  56  to low noise amplifiers  102  over paths  98 . Transmitted signals may be conveyed to power amplifiers  56  via paths  100 . Low noise amplifier circuitry  102  may amplify received radio-frequency signals before these signals are provided to radio-frequency transceiver circuitry  54  over paths  114 . Low noise amplifiers  102  may each include three gain stages (as an example). Radio-frequency signals that are to be transmitted may be conveyed from RF transceiver circuitry  54  to power amplifiers  56  over paths  100 . 
     Adjustable power supply circuitry  78  may be implemented using a DC/DC converter or any other suitable power conversion circuit. Circuitry  78  may receive a relatively higher voltage Vccbatt from battery  83  over power supply path  82  and may produce a corresponding regulated power supply voltage Vcc at a relatively lower voltage Vcc at output path  86 . In a typical arrangement, the battery voltage Vccbatt may range from about 4.3 volts to about 3.4 volts and output voltage Vcc may range from about 3.4 volts to 3.1 volts. The voltage Vcc may be adjusted based on control signals received over path  80 . Voltage Vcc may be adjusted continuously (e.g., to provide any desired output voltage in the range of 3.1 to 3.4 volts or other suitable range) or may be set to one of two or more discrete levels (e.g., 3.1 volts, 3.4 volts, etc.). The unregulated power supply voltage Vccbatt may be used in powering power amplifier circuitry  56 ′ (if desired). 
     Each power amplifier  56  may be used to handle a different communications band (e.g., bands at communications frequencies such as 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz). If desired, some or all of power amplifiers  56  may handle multiple communications bands (e.g., adjacent bands). 
     Power amplifiers  56  may receive control signals over path  76 . The control signals may be used to selectively turn on and off particular blocks of circuitry within each power amplifier. This type of adjustment may be used to place each power amplifier  56  in a desired gain mode. In a bimodal arrangement, each power amplifier may be placed in either a high gain mode or a low gain mode. If desired, other types of multimode arrangements may be supported (e.g., arrangements in which power amplifiers  56  can be adjusted to operate at three or more different gain settings.) 
     Baseband processor  52  may receive signals to be transmitted over antenna  62  at input line  106  (e.g., from processing circuitry  36 ). Baseband processor  52  may provide signals that are to be transmitted to RF transceiver circuitry  54 . Transmitted 2G signals may be provided to power amplifier circuitry  56 ′ over path  117 . Transmitted 3G signals may be provided to power amplifier circuitry  56  over paths  100 . Path  116  may be used to convey signals between baseband processor  52  and radio-frequency transceiver circuitry  54 . Clock sources such as oscillator  112  and oscillator  108  may be used to provide clock signals for the circuitry in devices  44 . As shown by lines  120 , signals from oscillator  112  may be shared with components other than radio-frequency transceiver circuitry  54 . Memory  104  may be used to store data for baseband processor  52 . Memory  104  may be, for example, 8-16 MB of static random-access memory (SRAM). 
     Batteries tend to lose voltage as they become depleted. A graph showing how the voltage Vccbatt at the output of battery  83  may decrease with time is shown in  FIG. 5 . As shown in  FIG. 5 , battery  83  may be characterized by a voltage versus time curve such as curve  122 . Initially, at time to, battery  83  may have a relatively high voltage (e.g., a voltage of greater than 4.0 volts). As the battery is used to power electronic components in device  10 , the battery becomes depleted and the magnitude of Vccbatt begins to fall. Eventually, the battery voltage Vccbatt drops to its lowest acceptable level (e.g., 3.4 volts) at time t end . 
     Components such as power amplifiers  56  do not always need to run at the maximum available battery voltage Vccbatt. Operating such components at battery voltages such as these can therefore waste power. To minimize the amount of wasted power, DC/DC converter circuitry  78  may be used to convert the unregulated and fluctuating voltage Vccbatt from its sometimes relatively high voltage levels to a more moderate, fixed power supply voltage level Vcc. The value of Vcc might be, for example, 3.1 volts or 3.4 volts (as an example). Because Vcc is significantly less than the maximum value of Vccbatt, power amplifiers  56  are not overpowered and may therefore be powered efficiently. 
     In accordance with embodiments of the present invention, the output of DC/DC converter  78  may be adjusted in real time to further minimize power consumption while ensuring the power amplifiers  56  can operate satisfactorily to meet time-varying operating constraints (e.g., desired output power levels, desired noise levels, etc.). Consider, as an example, a situation in which device  10  receives a transmit power command (TPC) from a wireless network that informs device  10  that the amount of required radio-frequency power that is to be transmitted in a particular communications band is fairly low. In this type of situation, it is not necessary to operate the power amplifier  56  corresponding to that communications band at its highest voltage. Rather, a reduced voltage Vcc may be used. As a result, device  10  can instruct DC/DC converter  78  to produce a voltage Vcc at its output of 3.1 volts, as indicated by dashed line  124  in  FIG. 5 . If, on the other hand, device  10  receives a command indicating that the output power from device  10  should be maximized, DC/DC converter  78  may be used to produce a higher power supply voltage Vcc such as a 3.4 volt voltage Vcc corresponding to dashed line  126  of  FIG. 5 . 
     Adjustments to Vcc may be made in real time to accommodate different radio-frequency (RF) output power needs for device  10 . The gain setting for amplifiers  56  may also be adjusted in real time as needed to meet the output power needs of device  10  while conserving power consumption when possible. The performance of devices  44  of  FIG. 4  in a situation in which both power supply voltage adjustments to Vcc and gain level adjustments to power amplifiers  56  are being made is illustrated by the graph of  FIG. 6 . In  FIG. 6 , the current consumption of power amplifier  56  is plotted as a function of radio-frequency output power P. The trace of  FIG. 6  shows how both adjustments to power supply voltage Vcc and adjustments to the amplifier&#39;s gain mode setting affect output power and current consumption 
     Consider, as an example, the situation in which an output power of P 4  is required. In this case, power amplifier  56  may be placed in a “high gain” mode in which all of its gain stages are active. To achieve maximum output power, power amplifier  56  may also be operated at a Vcc voltage of 3.4 volts by proper adjustment of DC/DC converter  78 . This set of operating conditions is characterized by line segment  124  of  FIG. 6 . 
     If a lower output power such as power P 3  is required, it may be possible to reduce the amount of current consumed by the power amplifier by lowering the voltage Vcc to a value such as 3.1 volts. As shown by line segment  126  of  FIG. 6 , this results in a lowering of the amount of current consumed by power amplifier  56 . 
     If an output power of P 2  is required, it may be possible to further reduce current consumption by adjusting the gain mode setting of the power amplifier. Power amplifier  56  has gain stages that can be selectively disabled when they are not needed. This allows power amplifier  56  to be placed in a configuration in which less current is consumed. When only an output power of P 2  is required, power amplifier  56  may be placed in its “low gain” mode by shutting off one or more of its gain stages. As indicated by line segment  128 , during this portion of the low gain mode operation of power amplifier  56 , the output of DC/DC converter (power supply Vcc) may be set to its high voltage setting of 3.4 volts to ensure that appropriate operating constraints are satisfied (e.g., signal-to-noise constraints, etc.). 
     As shown by line segment  130 , another operating configuration is possible. For example, when the required output power is P 1 , both the gain mode of the power amplifier and the power amplifier&#39;s power supply voltage Vcc may be reduced. When operating in “low gain” mode at a voltage of 3.1 volts, current consumption is minimized. 
     If desired, the magnitude of power supply voltage Vcc may be adjusted among more than two different discrete operating voltages or may be adjusted continuously. A graph showing how an adjustable power supply circuit such as an adjustable dc-to-dc converter with a continuously variable output voltage Vcc may provide a radio-frequency power amplifier with suitable power supply voltages Vcc at various different power amplifier gain settings according to required values of transmitted radio-frequency power P is shown in  FIG. 7 . 
     As shown in  FIG. 7 , a power amplifier such as one of power amplifiers  56  may be characterized by three gain settings (as an example). In the  FIG. 7  example, various gain stages in power amplifier  56  may be selectively enabled so that power amplifier may be set to operate in one of three gain modes. In the highest of the three gain modes, the power amplifier may be characterized by line “H.” In the lowest of the three gain modes, the power amplifier may be characterized by line “L.” In an intermediate gain mode, the power amplifier may operate according to line “M.” 
     The curves of  FIG. 7  show how the power supply voltage Vcc for the power amplifier may be reduced to minimize power consumption. The amount of power that may be saved depends, in general, on the amount of output power that is required at the output of power amplifier  56 . When required (e.g., in accordance with a wireless network TPC instruction or other requirement), the power amplifier may be operated in its maximum gain mode and at its highest operating voltage Vcc. For example, when an output power of 25 dBm is required (in the  FIG. 7  example), the power amplifier may be placed in its high gain mode and may be powered with a power supply voltage of Vh 2 . When a lower output power is required, such as 23 dBm, it is no longer necessary to operate the power amplifier at Vh 2 . Rather, the power supply voltage for the power amplifier may be reduced to a Vcc value of Vh 1 . This helps reduce power consumption. If an output power of 19 dBm is required, power consumption can be reduced further by placing the power amplifier in its medium gain mode and reducing the power supply voltage to Vm 2 . If less power is required (e.g., 17 dBm), the power supply voltage can be reduced further to Vm 1 . At still lower values of required output power, the power amplifier can be placed in its lowest gain mode (characterized by line L). If, as an example, 13 dBm of output power is needed, the power amplifier may be operated at a power supply voltage of V 12 . If only 10 dBm of output power is required, the power supply voltage produced by the adjustable power regulator may be reduced to V 11 . 
     As the example of  FIG. 7  illustrates, both gain mode adjustments and power amplifier power supply voltage adjustments can be used in reducing power consumption for power amplifier  56 . If desired, the potential inefficiencies of DC/DC converter  78  under certain operating conditions may be taken into account when making adjustments of this type. As shown in  FIGS. 8 and 9 , the efficiency of DC/DC converter  78  (and other such power regulator circuitry) may be affected by the operating voltage Vcc and operating current Icc that DC/DC converter  78  produces at its output. At high output voltages Vcc and high output currents Icc, adjustable power supply circuitry such as DC/DC converters may operate at peak efficiency. At lower Vcc and Icc levels, efficiency tends to drop. It may therefore be most efficient to reduce power supply voltage Vcc only in situations in which the power amplifier power savings that are obtained by reducing Vcc are not offset by increases in power consumption in DC/DC converter  78 . When Vcc is reduced, the values of power supply current and voltage that are used in powering power amplifier  56  tend to fall and overall power consumption will be reduced, so long as the reductions in power amplifier power consumption are not overwhelmed by power losses due to operating power supply circuitry  78  in an inefficient regime. 
     Consider, as an example, the graph of  FIG. 10 . In this example, power amplifier  56  has only a single gain setting. As shown in  FIG. 10 , at a required power amplifier output power of P 1 , it may be necessary to operate the power amplifier with a relatively large power supply voltage Vcc 3 . If less output power is required for a given set of operating conditions, power consumption may be minimized by reducing Vcc. For example, if the output power level that is required is P 2 , it may be possible to save power by reducing the power supply for power amplifier  56  to Vcc 2 . Sometimes even lower output powers are required, such as output power P 4 . If the inefficiencies associated with operating DC/DC converter  78  at low currents and voltages were neglected, it might be possible to minimize power consumption by operating power amplifier  56  at voltage Vcc 3 . However, in practice, the inefficiencies associated with operating DC/DC converter  78  at low current and voltage levels can cause the power consumption by DC/DC converter  78  to become increasingly significant at low output power levels. As a result, overall power consumption in device  10  may be minimized by restricting the minimum value of Vcc that is supply to power amplifier  56  by DC/DC converter  78 . In this type of arrangement, the voltage Vcc that is applied to power amplifier  56  may follow dashed line  132  rather than solid line  134  for output powers below about P 3 . 
     Power conversion inefficiency in DC/DC converter  78  may also affect the operation of device  10  in scenarios in which power amplifiers  56  are adjusted between various gain settings. This type of situation is illustrated in  FIG. 11 . As shown in  FIG. 11 , at a high output power such as power PA, it may be desirable to operate power amplifier  56  in a high gain mode, characterized by high gain line H, while powering power amplifier  56  at a Vcc level of V 1 . If less power is required, power consumption can be minimized by reducing Vcc. For example, when the output power requirement is PB, power amplifier  56  may be operated at voltage V 2 . 
     At particularly low output powers such as output power PE, the lowest overall power consumption for device  10  may be obtained by placing power amplifier in low gain mode, characterized by line L and by reducing Vcc to V 5 . 
     Depending on the efficiency of DC/DC converter  78 , it may or may not be beneficial to switch power amplifier  56  to low gain mode when producing intermediate output power levels. When power amplifier  56  is switched from high gain mode to low gain mode, the amount of current drawn by power amplifier  56  decreases. The amount of current consumed by power amplifier  56  is therefore generally less when power amplifier  56  is operated according to line L of  FIG. 11  rather than line H of  FIG. 11 . However, because of the inefficiencies of  FIGS. 8 and 9 , the overall amount of power consumed by device  10  may increase when power amplifier  56  is switched to low gain mode. 
     At a required output power level of PD, there are two possible operating scenarios in the example of  FIG. 11 . In the first scenario, power amplifier  56  is operated in high gain mode (line H) at a power supply voltage V 6 . In the second scenario, power amplifier  56  is operated in low gain mode (line L) at power supply voltage V 4 . When power amplifier  56  is operated in low gain mode, some of its circuitry is disabled (i.e., a power amplifier gain stage is turned off). This generally allows power consumption to be reduced. As a result, if DC/DC converter  78  is fairly efficient, it may be possible to minimize overall power consumption by operating power amplifier  56  in low gain mode (line L) at voltage V 4 . However, when power amplifier  56  is switched to low gain mode (line L), the amount of current drawn by power amplifier  56  may drop significantly. As a result, DC/DC converter  78  may be forced to operate in an inefficient low current regime, as shown in  FIG. 9 . The increased power consumption that results when operating DC/DC converter  78  in its low efficiency regime may overwhelm the potential power consumption savings when operating power amplifier in its low gain mode. It may therefore be more efficient to operate power amplifier  56  in its high gain mode (line H) at power supply voltage V 6 . Eventually, at particularly low output power requirements, the power savings from low gain mode operation may outweigh the increased power consumption in DC/DC converter  78 . It may therefore be beneficial to operate power amplifier  56  in low gain mode (line L) using a power supply voltage of V 5  when an output power of PE is required. 
     As this example demonstrates, it may not always be optimal to switch between higher and lower gain modes as soon as the lower gain modes become available. It may not, for example, be beneficial to switch to low gain mode when producing power PC (using power supply voltage V 3 ). It may only be beneficial to switch to low gain modes at lower output power scenarios such as below output power PD (as an example). 
     Illustrative steps involved in using radio-frequency power amplifier gain and power supply voltage adjustments to manage power consumption in wireless communications circuitry for a portable electronic device are shown in the flow chart of  FIG. 12 . At step  136 , device  10  may receive desired radio-frequency signal output power settings. For example, network equipment that is monitoring the received signal quality from multiple handsets may send a transmit power control (TPC) instruction to device  10 . The TPC instruction may specify a desired output power level for device  10  to use in transmitting radio-frequency signals. This power level may be selected by the network equipment to reduce interference with other devices in the network while maintaining adequate signal strength for supporting wireless communications. 
     At step  138 , processor  36  may compute an optimum setting for the gain of power amplifier  56  (e.g., how many gain stages in amplifier  56  are to be enabled) and an optimum setting for the output of DC/DC converter  78  based on expected levels of power consumption at various power supply voltages Vcc and gain settings (gain modes). These settings may be computed by custom logic, using a general purpose processor, using a processor associated with baseband functions (e.g., baseband processor  52  of  FIG. 4 ), or using a combination of these circuits or other suitable circuitry. If desired, the optimal settings that are computed may take into account the efficiency characteristics of DC/DC converter  78  at various current and voltage levels. 
     At step  140 , the settings of device  10  may be adjusted. For example, DC/DC converter  78  may be adjusted to produce a desired value of Vcc at its output and power amplifier circuit  56  may be adjusted to place it into a desired gain mode. 
     As indicated by line  142 , control may then loop back to step  136 . The process of  FIG. 12  may be performed continuously (as an example) whenever it is desired to communicate using wireless communications devices  44  (and power amplifiers  56 ). 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20080425
Publication Date: 20120828
Grant Date: 20120828
Priority Date: 20080425
Inventors: SORENSEN ROBERT
DIMPFLMAIER RONALD WILLIAM
Assignee: APPLE INC
CPC Classifications: [{"code": "H03F3/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F1/0244", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F1/0216", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F1/0216", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03G3/3042", "inventive": true, "first": true, "tree": "[]"}, {"code": "H03F3/195", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F1/0244", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F2200/405", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03F2200/405", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03G3/3042", "inventive": true, "first": true, "tree": "[]"}, {"code": "H03F2200/387", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03F3/195", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F2200/414", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03F2200/387", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03F3/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F2200/414", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 41215521