AU4463200A

AU4463200A - System and method for selectively controlling amplifier performance

Info

Publication number: AU4463200A
Application number: AU44632/00A
Authority: AU
Inventors: Patrick S. Cantey III; Ronald J. Fay; Christopher B Martin
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 1999-04-16
Filing date: 2000-04-13
Publication date: 2000-11-02
Also published as: JP2002542708A; CN1352826A; CA2370209A1; WO2000064062A1; EP1175732A1; KR20020005686A

Description

WO 00/64062 PCT/US00/10239 SYSTEM AND METHOD FOR SELECTIVELY CONTROLLING AMPLIFIER PERFORMANCE BACKGROUND OF THE INVENTION 5 I. Field of Invention This invention relates to amplifiers. Specifically, the present invention relates to systems and methods for improving the performance of and 10 extending the battery life of wireless phones and accompanying cellular telecommunications systems by selectively controlling power amplifier performance. II. Description of the Related Art 15 Cellular telecommunications systems are characterized by a plurality of mobile transceivers, such as mobile phones (also called wireless phones, mobile stations, or cellular telephones) in communication with one or more base stations. 20 Wireless phones include a transceiver having a transmit section and a receive section. In the receive section of a typical transceiver, an analog radio frequency (RF) signal is received by an antenna and downconverted by an RF section to an intermediate frequency (IF). Signal processing circuits perform noise filtering and adjust the magnitude of the signal via analog automatic gain 25 control (AGC) circuitry. An IF section then mixes the signal down to baseband and converts the analog signal to a digital signal. The digital signal is then input to a baseband processor for further signal processing to output voice or data. Similarly, the transmit section receives a digital input from the baseband 30 processor and converts the input to an analog signal. This signal is then filtered and upconverted by an IF stage to an intermediate frequency. The gain of the transmit signal is adjusted and the IF signal is upconverted to ultrahigh frequency (UHF) in preparation for radio transmission. Wireless phones transfer voice or data signals between other wireless 35 phones or land based telephones via a base station and/or a mobile switching WO 00/64062 PCT/US00/10239 2 center. A public switched telephone network (PSTN) communicates with the base station or mobile switching center and facilitates the routing of signals between land based phones and the wireless network. A large base station may govern a region divided into several cells, each cell associated with a base 5 station transceiver subsystem (BTS). Alternatively, a single base station may govern a particular cell associated with a given geographic region. The communications link (forward or reverse link) between a base station or BTS and a mobile station is a fading channel, which is a channel that is severely degraded. The degradation results from numerous effects including 10 multipath fading, severe attenuation due to the receipt via multiple paths of reflections of the transmitted signal off objects and structures in the atmosphere and on the surface, and from interference caused by other users of the communications system. Other effects contributing to the impairment of the faded channel include Doppler shift due to the movement of the receiver 15 relative to the transmitter and additive noise. The ability to operate efficiently in noisy or faded environments is particularly important in code division multiple access (CDMA) wireless communications systems where Raleigh-faded signal environments and co channel interference from other users are common. Raleigh fading results from 20 Doppler frequency shifts in the received signal due to mobile station movement. Co-channel interference occurs when a CDMA communications system maintains multiple system users, with each additional user contributing incrementally to the co-channel interference. Co-channel interference is typically larger than other forms of channel noise such as additive white 25 Gaussian noise (AWGN). In a Raleigh-faded signal environment, the power levels of transmitted communications signals fluctuate in accordance with a Raleigh distribution. The power typically fluctuates over a dynamic range of 10dB to 50dB. The duration of the fades is a function of the velocity of a mobile station, i.e., cellular 30 telephone, the frequency channel assigned to the mobile station, and overall signal environment. As the velocity of a mobile unit increases, fade duration decreases, leading to shorter error bursts. As the velocity of the mobile unit decreases, fade duration increases, leading to longer error bursts.

WO 00/64062 PCT/US00/10239 3 When a wireless phone transmits a signal such as a voice signal to a base station, the requisite power of the transmitted signal depends on the interference characteristics of the channel, which often varies in accordance with the relative proximity of the wireless phone to the associated base station. 5 When in close proximity to a base station, a wireless phone requires less power to effectively communicate with an associated base station. The requisite power level of the signal transmitted by the wireless phone varies in accordance with the varying noise and fading characteristics of the channel. Some wireless phone technologies fail to account for the varying 10 power requirements and instead broadcast continuously at full power. This results in reduced phone battery life and may contribute to increased channel interference. To account for the varying power levels, many conventional wireless phones employ automatic gain control circuitry to adjust the gain of the signal 15 in the transmit section. The phones may switch between high and low power modes depending on the proximity of the phone with respect to a transmitting base station and/or the interference characteristics of the channel between the base station and the wireless phone. When the wireless phone is near the base station, the channel introduces less interference to the transmitted signal, and 20 the power level of the transmitted signal is reduced accordingly to save power and extend the battery life and talk time of the wireless phone. Unfortunately, the use of conventional automatic gain control circuitry alone is insufficient to maximize the performance and power consumption of the telephone. Wireless phones include additional power amplifiers and filters, 25 whose performance and power consumption vary with temperature as well as signal operating environment. Existing systems fail to effectively control the power consumption and performance of these additional amplifiers and fail to efficiently accommodate temperature variations to maximize phone performance and battery life. Wireless phones often include a power amplifier, 30 whose efficient performance is particularly important for extending battery life and associated talk time. Hence, a need exists in the art for an efficient system and method for maximizing wireless phone performance and extending phone battery life and talk time. There is a further need for an efficient system for controlling power WO 00/64062 PCT/US00/10239 4 consumption of power amplifiers within the wireless phone that accounts for temperature variations. SUMMARY OF THE INVENTION 5 The need in the art is addressed by the system for extending the battery life of a wireless phone of the present invention. In the illustrative embodiment, the inventive system is adapted for use with code division multiple access (CDMA) transceiver and includes a first circuit for providing a control signal 10 indicative of a mode of the wireless phone. A second circuit provides a transmit signal. A third circuit amplifies the transmit signal in preparation for transmission. The third circuit requires a biasing signal. A fourth circuit selectively alters the power dissipated by the third circuit by selectively changing the biasing signal in response to the control signal. 15 In a specific embodiment, the fourth circuit includes a circuit for determining a desirable operational mode of the system as indicated by the control signal. The fourth circuit is called an efficiency circuit and also includes a circuit for adjusting the biasing signal in accordance with the desirable operational mode of the system. A voltage divider circuit in the efficiency 20 circuit has a node between a first impedance circuit and a second impedance circuit. The first impedance circuit includes a switch for altering the impedance of the first impedance circuit in accordance with the desirable operational mode. The first impedance circuit includes a first resistor in parallel with a second resistor. The switch is a transistor for isolating the first resistor or the 25 second resistor from the voltage divider in accordance with the desirable operational mode. The first circuit for providing the control signal includes a digital chip or phone modem. The digital chip runs software for establishing the control signal in response to the detection of an operating environment of the wireless 30 phone and accompanying system. A receiver provides information to the software to help determine the operational mode. The mode is a high-power mode or a low-power mode associated with an electrically noisy signal environment or an electrically clear signal environment, respectively, as indicated by the information.

WO 00/64062 PCT/US00/10239 5 The second circuit has a transmit path that includes the digital chip connected to an automatic gain control circuit connected to an intermediate frequency to radio frequency mixing circuit that is connected to a filter section. The filter section outputs the transmit signal. 5 The novel design of the present invention is facilitated by the unique efficiency circuit of the present invention. The efficiency circuit selectively controls the power consumption, gain, and/or performance with respect to temperature of the third circuit, which acts as a power amplifier, according to a power-mode of the wireless phone, signal operating environment, and/or 10 temperature. As a result, control over the performance of the third circuit is greatly enhanced, which results in improved phone battery life and talk time as well as improved performance with respect to variations in temperature. BRIEF DESCRIPTION OF THE DRAWINGS 15 Fig. 1 is a diagram of a wireless phone transceiver having an efficiency circuit constructed in accordance with the teachings of the present invention. Fig. 2 is a more detailed diagram of the efficiency circuit of Fig. 1. Fig. 3 is an alternative embodiment of the efficiency circuit of Fig. 2. 20 DESCRIPTION OF THE INVENTION While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood 25 that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. Fig. 1 is a diagram of a wireless phone transceiver 10 having an efficiency 30 circuit 12 constructed in accordance with the teachings of the present invention. For clarity, several details such as speakers, microphones, vocoders, clocking circuitry, reference oscillators and other circuits of the transceiver 10 have been omitted from Fig. 1. With access to the present teachings, those ordinarily skilled in the art will know where to position and how to implement the 35 additional circuitry.

WO 00/64062 PCT/US00/10239 6 The transceiver 10 is implemented as a wireless code division multiple access (CDMA) phone and includes a battery 14 that powers the transceiver 10. The transceiver 10 includes a transmit path 16 and a receive path 18. The transmit path 16 includes, from left to right, a digital control chip 20, an 5 automatic gain control (AGC) circuit 22, an intermediate frequency (IF) to radio frequency (RF) mixer 24, a driver 28, a power amplifier (PA) 32, an isolator 33, a duplexer 34, and an antenna 36. The receive path 18 also includes the antenna 36, the duplexer 34, the digital control chip 20, and further includes a receive section 38 connected between the duplexer 34 and the digital control chip 20. 10 The battery 14 is connected to the digital control chip 20, the AGC 22, the mixer 24, the receive section 38, the driver 28, the power amplifier 32, and the efficiency circuit 12. An output of the efficiency circuit 12 is connected to a biasing input of the power amplifier 32. In operation, the duplexer 34 facilitates the sharing of antenna resources 15 between transmitting functions and receiving functions implemented via the transmit path 16 and the receive path 18, respectively. The isolator 33 isolates the power amplifier 32 from the antenna 36 and duplexer 34 and prevents power reflection back from the antenna 36 to the power amplifier 32. Signals received by the antenna 36 are routed to the receive section 38 via 20 the duplexer 34. The receive section 38 contains filters and signal mixing and downconversion circuitry (not shown) that prepare the received signal for processing via a baseband processor (not shown) included in the digital control chip 20. Those ordinarily skilled in the art can easily design and implement the receive section 38 to suit the needs of a given application. The antenna 36, 25 duplexer 34, receive section 38, and the digital control chip 20 implement the receiver portion of the wireless phone transceiver 10. The digital control chip 20 includes a digital signal processor known as a baseband processor (not shown), a mobile station modem, and other processing circuitry for running software and controlling the operation of the wireless 30 phone 10. The digital control chip 20 includes analog-to-digital converters (ADCs) (not shown) for converting analog signals from the receive path to digital signals and includes digital-to-analog (DACs) (not shown) for converting digital signals from the baseband processor to analog signals in preparation for transmission via the transmit path 16.

WO 00/64062 PCT/US00/10239 7 Analog transmit signals from the digital control chip 20 are input to the AGC 22 where the gain of the transmit signals is adjusted in accordance with a power mode of the transceiver 10 as determined via software or hardware in the digital control chip 20 as discussed more fully below. The transmit signals 5 are then converted to analog UHF signals via the up-converter 24, which acts as a mixer and is synchronized via oscillators (not shown) to an appropriate UHF frequency. The up-converted signals are then filtered and scaled via the first filter 26, the driver 28, and the second filter 30 to remove noise and prepare the transmit signals for transmission. The resulting filtered transmit signal is 10 amplified by the power amplifier 32, whose gain and power consumption is controlled via the efficiency circuit 12, which selectively changes a biasing signal 42 to the power amplifier 32 in response to the receipt of a control signal 40 from the digital control chip 20. The efficiency circuit 12 also stabilizes the performance of the amplifier 32 with respect to temperature by selectively 15 altering the biasing signal 42 in response to changing temperature. The efficiency circuit 12 stabilizes the performance of the amplifier 32 over the temperature range of -30oC to 110oC. The digital control chip 20 includes a baseband processor (not shown) that runs conventional software or hardware algorithms to measure a signal 20 amplitude or strength and provide a Receive Signal Strength Indication (RSSI) of the received signal in response thereto. The digital control chip 20 then provides the control signal 40 to the efficiency circuit 12 in response to the RSSI measurement. If the RSSI is high as compared to a predetermined threshold, the digital control chip 20 sets the transceiver 10 to a low-power mode by 25 issuing the control signal 40 to the efficiency circuit 12 and providing gain adjustment parameters to the AGC circuit 22. Similarly, if the RSSI is low, the digital control chip 20 sets the transceiver to a high-power mode. In low-power mode, the power of the signal transmitted from the digital control chip 20 via the transmit path 16 is reduced to account for the high quality of the channel as 30 indicated by the high RSSI measurement. Similarly, in high-power mode, the transceiver 10 broadcasts with more power, which is drawn from the battery 14. The predetermined threshold is application specific and may be easily adjusted by one ordinarily skilled in the art to meet the needs of a given application.

WO 00/64062 PCT/US00/10239 8 The efficiency circuit 12 adjusts the gain and resulting output signal power of the amplifier 32 by controlling the biasing signal 42. In the present specific embodiment, when the control signal 40 is in a low voltage state, the magnitude of the biasing signal 42 increases, which increases the gain and 5 power consumption of the amplifier 32. Similarly, when the control signal 40 is in a high voltage state, the magnitude of the biasing signal 42 decreases. The biasing signal 42 is a current signal when the power amplifier 32 is a heterojunction bipolar junction transistor (HBT) amplifier. The biasing signal 42 is a voltage signal when the power amplifier is a GaAs field-effect transistor 10 amplifier (GaAs FET). Fig. 2 is a more detailed diagram of the efficiency circuit 12 of Fig. 1. The battery 14 of Fig. 1 provides a varying battery voltage (Vcc) to a regulator 43, which regulates the varying voltage Vcc and provides an approximately constant voltage (Vreg) at a node 13 connected to a first end of a first resistor R1 15 and to a first end of a second resistor R2. A second end of the first resistor R1 is connected to a negative input terminal of an operational amplifier 50 and to a source of a p-channel metal oxide semiconductor field-effect transistor (MOSFET) 52. The gate of the p-channel MOSFET 52 is connected to an output of the operational amplifier 50. The drain of the p-channel MOSFET 52 is 20 connected to the power amplifier 32 and provides the biasing signal Iref 42 to a biasing terminal of the power amplifier 32. In the present specific embodiment, the power amplifier 32 is implemented as an HBT amplifier. The operational amplifier 50 is biased via standard circuitry (not shown) that operates in accordance with methods known in the art. A positive input 25 terminal of the operational amplifier 50 is connected at a node 15 that connects a second end of the second resistor R2, a first end of a fourth resistor R4, and a first end of a fifth resistor R5. A second end of the fifth resistor R5 is connected to ground. A second end of the fourth resistor R4 is connected to an emitter of pnp bipolar junction transistor (BJT) 54. A collector of the pnp BJT 54 is 30 connected to ground. The control signal 40 (Vcontrol) from the digital control chip 20 of Fig. 1 is provided to a first end of a third resistor R3. A second end of the third resistor R3 is connected to the base of the pnp BJT 54. The pnp BJT 54 acts as a switch that selectively connects the second end of the fourth resistor R4 to ground in response to a low voltage state provided WO 00/64062 PCT/US00/10239 9 via the control signal (Vcontrol) to a base of the pnp BJT 54 via the resistor R3. The transistor 54 may be replaced with another type of switch without departing from the scope of the present invention. The operation of the efficiency circuit 12 is such that when the control 5 signal Vcontrol 40 is in a low voltage state, such as 0 volts, the reference signal Iref is a function of the constant voltage Vreg provided by the regulator 43 of Fig. 1 as described by the following equation: Irf= % V1 'ref R 2

+R

4 11R 5 reg 10 where R4//R5 is the parallel operation defined in accordance with the following equation:

R

4

R

5 RnIIR-4 + R [2] 15 Choices for the values of the resistors R1, R2, R4 and R5 are application specific and may be easily adjusted by those ordinarily skilled in the art to meet the needs of a given application. In the present embodiment, R1 = 27.0 2, R2 = 392.0 O, R3 = 10.0 kM, R4 = 36.0 kM, and R5 = 18.0 kM, and Vreg = 3.0V. Vcc represents the voltage output by the battery 14 of Fig. 1, which may 20 vary over the charging cycle of the battery 14, while Vreg represents the constant DC reference voltage output from the voltage regulator 43. When the control signal Vcontrol 40 is in a high voltage state such as 5 volts, the reference signal Iref is a function of the constant voltage Vreg as described by the following equation: 25 R rf =2 R 5 Vreg [3] Since R5 > R4//R5, switching out the effect of R4 via the pnp BJT 54 and the control signal 40 results in a reduction in the biasing current Iref.

WO 00/64062 PCT/US00/10239 10 The control signal 40 selectively isolates R4 from the efficiency circuit 12 when the control signal 40 is in a high voltage state. The lack of the contribution of R4 causes a corresponding increase in the voltage (V+) at the positive input terminal of the operational amplifier 50 and an increase in the 5 voltage (V-) at the negative input terminal of the operational amplifier 50. The increased voltage decreases the current flowing through the first resistor R1 (in accordance with Ohm's Law) and hence through the source and drain of the p channel MOSFET 52. As a result, the current Iref decreases. It is well known in the art that for operational amplifiers, V+ = V- and I+ = I- = 0. 10 The fourth resistor R4 and the fifth resistor R5 form a first impedance circuit 57 that is connected to a second impedance circuit 59 at the node 15. The second impedance circuit 59 includes the first resistor R1, the second resistor R2, and the node 13 therebetween. The resistance of the first impedance circuit 57 is selectively changed via the transistor 54 and the control signal 40. When 15 the transistor 54 is on, the resistance of the first impedance circuit 57 is approximated by equation (2). When the transistor 54 is off, the fourth resistor R4 is isolated, and the resistance or impedance of the first impedance circuit 57 is the value of the fifth resistor R5. By selectively controlling the impedance of the first impedance circuit 57 via the control signal 40 and the transistor 54, the 20 biasing signal 42, i.e., the current Iref delivered to the power amplifier 32 is controlled. The resistance of the p-channel MOSFET 52 changes with temperature and helps to stabilize the performance of the amplifier 32 in operating environments characterized by temperature extremes. The p-channel MOSFET 25 52 may be replaced with another type of transistor or variable resistor without departing from the scope of the present invention. The requisite low and high voltage states of the control signal 40 required to turn on and off the pnp BJT 54, respectively, depend on transistor parameters, which may be chosen by those ordinarily skilled in the art to meet 30 the needs of a given application. Conventional transceivers for wireless phones lack the efficiency circuit 12 and fail to precisely control the performance of the power amplifier 32 in response to changing transceiver power modes or variations in temperature. Without the efficiency circuit 12, the performance of the power amplifier 32 WO 00/64062 PCT/US00/10239 11 may vary with temperature and significantly degrade the performance of the transceiver 10 in cold or hot environments or in electrically noisy or clear environments, resulting in excess power consumption and/or undesirable transceiver performance. 5 Those skilled in the art will appreciate that the efficiency circuit 12 may be expanded to accommodate more than two transceiver power modes without departing from the scope of the present invention. The various amplifiers 32 and 50, resistors R1 through R5, and transistors 52 and 54 may be ordered from a standard electronics supply house. 10 Fig. 3 is an alternative embodiment 60 of the efficiency circuit 12 of Fig. 1. The voltage Vcc from the battery 14 of Fig. 1 is provided to a voltage inverter 64, to a first biasing terminal of the operational amplifier 50, and to an input of a precision voltage reference generator 66. An output of the inverter 64 is connected to a second biasing terminal of the operational amplifier 50. An 15 output of the precision voltage reference generator 66 is connected to a first end of a sixth resistor R6 and to a first end of a seventh resistor R7 and provides a precision voltage reference Vref. A second end of the sixth resistor R6 is connected to a switch 68, which may be implemented as an n-channel FET. The second end of the sixth resistor 20 R6 is connected to a first end (such as to a drain of an n-channel FET) of the switch 68. The control signal 40 is provided to a control terminal (such as the gate of an n-channel FET) of the switch 68, which selectively connects, in response to the control signal 40, the second end of the sixth resistor R6 to a node 69. The node 69 is connected to a negative input terminal of the 25 operational amplifier 50, to a second end of the seventh resistor R7 and to a first end of an eighth resistor R8. The node 69 is connected to a second end (such as the source (S) of an n-channel FET) of the switch 68. A second end of the eighth resistor R8 is connected to an output terminal of the operational amplifier 50 and to a biasing terminal of a metal semiconductor field-effect transistor 30 (MESFET) amplifier 32', which in the present specific embodiment is a GaAs FET amplifier. A positive input terminal of the operational amplifier 50 is connected to a ground. The precision voltage Vref is a constant voltage whose value is application-specific and may or may not be equivalent to the constant voltage WO 00/64062 PCT/US00/10239 12 Vreg of Fig. 2 output from the voltage regulator 43 of Fig. 2. Vref and Vreg are highly stable and accurate DC reference voltages of predetermined values. Those ordinarily skilled in the art can easily determine an appropriate value for Vref or Vreg to meet the needs of given application. The precision voltage 5 reference generator 66 may be constructed by one skilled in the art from a voltage regulator, a voltage scaling circuit, or other similar circuitry. In operation, the voltage Vcc provided by the battery 14 of Fig. 1 is provided to the first biasing terminal of the operational amplifier 50 and to the inverter 64. The inverter 64 inverts the voltage +Vcc and provides a negative 10 battery voltage -Vcc to a second biasing terminal of the operational amplifier 50. The voltage reference Vref is a highly stable and accurate DC voltage of a predetermined value. The predetermined voltage value is application-specific and may easily be determined by one ordinarily skilled in the art to meet the needs of a given application. 15 The resistive contribution of the sixth resistor R6 to the efficiency circuit 60 is switched in and out in response to a high voltage state or a low voltage state respectively, provided to the control terminal of the switch 68 via the control signal 40. The switch 68 may be implemented with a transistor such as a FET. 20 When the control signal 40 is in a high voltage state, the biasing signal, i.e., voltage (Vgg) provided to the GaAs FET amplifier 32' is a function of the precision voltage reference Vref as described by the following equation: gg R 6 11R 7 /7 V..- &IRV | , [4] 25 where the parallel operation is as described above. In the present embodiment, R8 = 16.2 £2, R6 = 340.0 kQ, R7 = 13.3 kM, Vcc = 4.1 V to 3.2 V. When the control signal 40 is in a low voltage state, the switch 68 turns off, and the sixth resistor R6 is isolated. This causes the biasing voltage Vgg to 30 become more positive (assuming R7 > R6//R7), which is described by the following equation: WO 00/64062 PCT/US00/10239 13 R8' g 7 R .

[5] The sixth resistor R6 and the second resistor R7 are part of a first impedance circuit 57'. The eighth resistor R8 represents a second impedance circuit 59', which is connected to the first impedance circuit 57' at the node 69. The 5 resistance of the first impedance circuit 57' is selectively changed via the switch 68 and the control signal 40. When the switch 68 is on, the resistance of the first impedance circuit 57' is approximately R6 I R7. When the switch 68 is off, the sixth resistor R6 is isolated, and the resistance of the first impedance circuit 57' is the value of the seventh resistor R7. By selectively controlling the impedance 10 of the second impedance circuit 59' via the control signal 40 and the switch 68, the biasing signal Vgg delivered to the power amplifier 32' is controlled. Thus, the present invention has been described herein with reference to a particular embodiment for a particular application. Those having ordinary skill in the art and access to the present teachings will recognize additional 15 modifications, applications, and embodiments within the scope thereof. It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention. 20 WE CLAIM:

Claims

1. A system for extending the battery life of a wireless phone comprising: 2 means for providing a control signal indicative of a mode of said wireless phone; 4 means for providing a transmit signal; means for amplifying said transmit signal in preparation for 6 transmission, said means for amplifying requiring a biasing signal; and means for selectively altering power dissipated by said means for 8 amplifying by selectively changing said biasing signal in response to said control signal.

2. The system of Claim 1 wherein said means for selectively altering 2 includes means for determining a desirable operational mode of said wireless phone as indicated by said control signal.

3. The system of Claim 2 wherein said means for selectively altering 2 includes means for adjusting said biasing signal in accordance with said desirable operational mode.

4. The system of Claim 3 wherein said means for adjusting includes a 2 voltage divider circuit having a node between a first impedance circuit and a second impedance circuit.

5. The system of Claim 4 wherein said first impedance circuit includes a 2 switch for altering an impedance of said first impedance circuit according to said desirable operational mode.

6. The system of Claim 5 wherein said first impedance circuit includes a first 2 resistor in parallel with a second resistor.

7. The system of Claim 6 wherein said switch is a transistor for isolating 2 said first resistor or said second resistor from said voltage divider circuit in accordance with said desirable operational mode. WO 00/64062 PCT/US00/10239 15

8. The system of Claim 1 wherein said means for providing a control signal 2 includes a digital chip.

9. The system of Claim 8 wherein said digital chip includes software for 2 establishing said control signal in response to the detection of an operating environment of said wireless phone.

10. The system of Claim 9 further including a receiver, said receiver 2 providing information to said software to facilitate a setting of said mode.

11. The system of Claim 10 wherein said mode is a high-power mode or a 2 low-power mode associated with an electrically noisy signal environment or an electrically clear signal environment, respectively, as indicated by said 4 information.

12. The system of Claim 8 wherein said means for providing a transmit 2 signal includes said digital chip connected to an automatic gain control circuit connected to an intermediate frequency to radio frequency mixing circuit that is 4 connected to a filter section, an output of said filter section representing said transmit signal.

13. A system for extending the battery life of a wireless phone comprising: 2 means for providing a first control signal state indicative of a low power mode and a second control signal state indicative of a high power mode; 4 means for providing a transmit signal; means for amplifying said transmit signal by a predetermined factor in 6 preparation for transmission; and means for selectively altering power consumption of said means for 8 amplifying by reducing said factor in response to said first control signal and increasing said gain factor in response to said low power mode.

14. A system for improving the efficiency of a power amplifier comprising: 2 first means for determining a desirable operational mode of said power amplifier and providing a control signal in response thereto; WO 00/64062 PCT/US00/10239 16 4 second means for providing a biasing signal to said power amplifier; and third means for selectively altering said biasing signal in response to said 6 control signal.

15. An efficient transceiver comprising: 2 first means for receiving a first signal and measuring a predetermined characteristic thereof and providing a control signal in response thereto; 4 second means for selectively setting a state of said transceiver to a predetermined transceiver mode in response to said control signal; 6 third means for providing a second radio frequency signal; fourth means amplifying said second radio frequency signal by a gain 8 factor/bias; fifth means for selectively altering said gain factor/bias in response to 10 said predetermined transceiver mode.

16. The transceiver of Claim 15 wherein said fifth means further includes a 2 means for limiting temperature-induced variations of said gain factor/bias.

17. The transceiver of Claim 16 wherein said means for limiting 2 temperature-induced variations of said gain factor/bias includes an operational amplifier having an output connected to a base or gate of a transistor.

18. The transceiver of Claim 17 wherein said transistor is a p-channel metal 2 oxide semiconductor field-effect transistor.

19. The transceiver of Claim 15 wherein said predetermined transceiver 2 mode is either a low-power mode or a high-power mode.

20. The transceiver of Claim 15 wherein said predetermined characteristic of 2 said first signal is a magnitude of an interference component of said first signal.

21. The transceiver of Claim 15 wherein said fourth means includes a power 2 amplifier. WO 00/64062 PCT/US00/10239 17

22. The transceiver of Claim 15 wherein said fourth means includes a 2 heterojunction bipolar transistor amplifier.

23. The transceiver of Claim 15 wherein said fourth means includes a metal 2 semiconductor field-effect transistor amplifier.

24. The transceiver of Claim 15 wherein said metal semiconductor field 2 effect transistor amplifier is a GaAs field-effect transistor and said first means for receiving includes a receiver and a digital chip.

25. The transceiver of Claim 24 wherein said digital chip runs software for 2 computing a signal strength of said first signal and providing said control signal in response thereto.

26. The transceiver of Claim 25 wherein second means includes a means for 2 setting said transceiver to a low-power mode in response to a high signal strength.

27. The transceiver of Claim 26 wherein said second means includes means 2 for setting said transceiver to a high-power mode in response to a low signal strength.

28. An efficient transmitter comprising: 2 a digital chip for providing an intermediate frequency signal and a mode setting signal; 4 an automatic gain control circuit for amplifying said intermediate frequency signal to a predetermined level and providing an amplified 6 intermediate frequency signal in response thereto; a frequency conversion circuit for converting said amplified intermediate 8 frequency signal to a radio frequency signal; a filter for filtering said radio frequency signal and providing a filtered 10 radio frequency signal in response thereto; WO 00/64062 PCT/US00/10239 18 a power amplifier for amplifying said radio frequency signal in 12 preparation for transmission and providing an amplified radio frequency signal in response thereto; 14 a power consumption control circuit for selectively adjusting power consumption of said power amplifier in response to said mode setting signal; 16 and an antenna for transmitting said amplified radio frequency signal.

29. A method for extending the battery life of a wireless phone comprising 2 the steps of: generating a control signal indicative of a mode of said wireless phone; 4 providing a transmit signal; amplifying said transmit signal in preparation for transmission, said 6 means for amplifying requiring a biasing signal; and selectively altering power dissipated in said step of amplifying by 8 selectively changing said biasing signal in response to said control signal.