Abstract: A variable gain power amplifier includes a power amplifying unit and a signal generating unit. The power amplifying unit includes a control terminal, and a gain of the power amplifying unit is variable by a control signal provided through the control terminal. The signal generating unit generates the control signal to be provided to the control terminal. The signal generating unit includes a switching circuit to be turned on and off by a binary signal, a constant current source that generates a constant current, and a variable current source that generates a variable current. Also, the signal generating unit generates, when the switching circuit is on, a control signal of a magnitude that turns on the power amplifying unit and depends on a magnitude of a sum of the constant current and the variable current. When the switching circuit is off, the signal generating unit generates a control signal of a magnitude that turns off the power amplifying unit.

Abstract: A power amplifier circuit including a first transistor, a second transistor, and a power control circuit. The first transistor includes a first input and a first output. The second transistor includes a second input coupled in series with the first output of the first transistor. The input circuit is coupled to the second input of the second transistor. The control circuit includes a time delay circuit and a variable source.

Abstract: A bias control signal generation unit detects ON and OFF of a transmission signal input to an amplifier and having a property of a burst according to burst information. The bias control signal generation unit controls a bias voltage to be applied to an amplifier such that an idle current flowing through the amplifier can be flowing in a larger amount in a transmission OFF period, and can return to a normal level in a transmission ON period.

Abstract: Aspects of a method and system for polar modulating OFDM signals with discontinuous phase may include amplifying an OFDM signal via a plurality of amplifiers such that a combined gain of the plurality of amplifiers comprises a coarse amplitude gain and an amplitude offset gain. A gain of one or more of the plurality of amplifiers may be adjusted to set the coarse amplitude gain, and a gain of one or more remaining ones of the plurality of amplifiers may be adjusted to set the amplitude offset gain. The setting of the coarse amplitude gain and/or the amplitude offset gain may be adjusted dynamically and/or adaptively.

Abstract: A bias circuit 12 includes: a transistor Q5 operable to supply, to an amplifier 11, a bias current in accordance with a base current supplied thereto; a transistor Q3 operable to pass a current in accordance with a reference voltage Vref; a transistor Q2 operable to correct, in accordance with the current passed by the transistor Q3, the base current to be supplied to the transistor Q5, so as to compensate a temperature characteristic represented by the transistor Q5; and a bias changing section (of a transistor Q4, and resistances R5, R6, and R7), connected to a base of the transistor Q5, operable to change, in accordance with a control voltage VSW, an amount of the base current to be supplied to the transistor Q5. The amplifier 11 amplifies, by using the bias current supplied by the bias circuit 12, a radio frequency signal having been inputted thereto.

Abstract: Embodiments of the invention may provide for enhancement systems and methods for a power amplifier output control system. In an example embodiment, driver amplifier control may be provided in conjunction with power amplifier control to improve the power efficiency and/or dynamic range of the transmitter system. Furthermore, control over the driver amplifier may allow for relaxed power control slope, which may lessens the burden of digital to analog converters (DACs) in transmitter systems such as cellular transmitter systems. Also, systems and methods in accordance with example embodiments of the invention may provide a less sensitive solution to operational environment variations such as temperature, battery power voltage and implementation IC process.

Abstract: A transconductance compensating bias circuit is disclosed that includes a first field-effect transistor (FET) having a first electrode, a second electrode, and a gate connected to the first electrode, wherein a reference current flows through the first and second electrodes; a second FET having a first electrode, a second electrode, and a gate connected to the gate of the first FET, wherein a bias current flows through the first and second electrodes; a resistor connected to the second electrode of the first or second FET; and a comparison part configured to output a signal corresponding to the result of comparison of the first potential of the first electrode of the first FET and the second potential of the first electrode of the second FET. The reference current and the bias current are controlled by the output signal of the comparison part so as to equalize the first and second potentials.

Abstract: A variable-gain amplifier includes an intermediate node operative to receive an electric current from a current source. A common-emitter amplifier has a collector electrically connected to the intermediate node. A first common-base amplifier has an emitter electrically connected to the intermediate node and a collector electrically connected to an output node. A base-degenerated amplifier has an emitter electrically connected to the intermediate node and a collector electrically connected to the output node. A second common-base amplifier has an emitter electrically connected to the intermediate node and a collector electrically connected to small-signal ground.

Abstract: In a high frequency power amplifier circuit that supplies a bias to an amplifying FET by a current mirror method, scattering of a threshold voltage Vth due to the scattering of the channel impurity concentration of the FET, and a shift of a bias point caused by the scattering of the threshold voltage Vth and a channel length modulation coefficient ? due to a short channel effect are corrected automatically. The scattering of a high frequency power amplifying characteristic can be reduced as a result.

Abstract: A method and apparatus for dynamically biasing a class AB RF power amplifier (PA) over a range of output power levels. A memory 112 holds a table that maps a required output power to the PA from a set of bias point parameters that provide a substantially constant relative power amplifier linearity level for the PA over an output power range of the power amplifier. A bias circuit 104 biases the PA. A processor 106 obtains an output power level from the PA, recalls the bias point table from the memory, maps the power level to the corresponding bias point parameters, and directs the bias circuit to bias the power amplifier in response to the mapped bias point parameters to provide an optimal linearity performance over an operating output power range of the PA.

Abstract: A method and circuit for preserving linearity of a RF power amplifier, the power amplifier including a RF power output unit having a characteristic drive level and fed by a supply voltage, comprising measuring the output voltage of the RF power output unit; comparing the measured output voltage to at least one threshold voltage to produce a control signal; and adapting the drive level or the supply voltage of the RF power output unit by means of the control signal to operate the output unit below its saturation level. A method and circuit for stabilizing an antenna circuit comprising a RF power amplifier and a matching circuit by preserving linearity of a RF power amplifier, where the above power amplifier is used.

Abstract: According to one exemplary embodiment, a power supply rejection bias circuit includes a first amplifier coupled to a second amplifier, where the first amplifier receives a reference voltage, and a feedback voltage of the bias circuit. The bias circuit further includes an output transistor driven by the output of the second amplifier, where the output transistor provides the output of the bias circuit and the feedback voltage. The bias circuit further includes a feedback resistor coupled between an input and an output of the second amplifier. According to this embodiment, the output of the second amplifier forms a non-dominant pole of the bias circuit and the output of the bias circuit forms a dominant pole of the bias circuit, thereby increasing power supply rejection of the bias circuit.

Abstract: The present invention discloses an adjustable gain power amplifier circuit. The adjustable gain power amplifier circuit includes a power amplifying unit for receiving and amplifying an input signal to generate an output signal; a power detecting unit for detecting power of the input signal to generate a detecting signal; and a biasing control unit for generating a biasing signal according to the detecting signal and to output the biasing signal.

Abstract: Provided is circuitry for biasing a transistor amplifier with a DC-voltage signal, the transistor amplifier having a first input terminal, a second input terminal, and an output terminal coupled to the second input terminal. The circuitry includes a sensor capacitor connected to the first input terminal and an impedance transistor arranged in parallel with said capacitor, the transistor and capacitor forming a low-pass filter. The circuitry also includes a biasing circuit configured to controllably vary a DC-voltage signal for operatively biasing the amplifier, the biasing circuit including a cascaded current arrangement configured to subdivide a reference current into smaller currents for selectively generating voltage potentials for biasing the impedance transistor to adjustably filter a noise component of the DC-voltage signal via the low-pass filter before the DC-voltage signal is provided to the first input terminal.

Abstract: A disclosed self regulating biasing circuit (SRBC) includes an unregulated node that couples to an unregulated power supply that produces a supply voltage. An impedance element of the SRBC carries an unregulated current having a nominal component and a variance component between an unregulated node and a regulated node. A detection circuit connected between the unregulated node and a third node detects a variance component of a supply voltage and generates a detection current based on the variance component. A compensation circuit connected to the third node draws a compensation current, based on the detection current, from the regulated node. The SRBC is designed wherein the compensation current is approximately equal to the variance component of the unregulated current. The regulated node may be connected to a control terminal of a transistor to be biased.

Abstract: An amplifier circuit for amplifying a high-frequency input signal comprises an amplifier stage, which amplifies the high-frequency input signal as a function of an operating point of the amplifier stage and generates an operating point-dependent signal, an observer stage, which replicates the amplifier stage and generates an observation signal, a regulator, which is supplied with the operating point-dependent signal and the observation signal, and an control element, which influences the operating point of the amplifier stage and is driven by the regulator, whereby the regulator drives the control element in such a way that the operating point of the amplifier stage is substantially independent of a level of the high-frequency input signal.

Abstract: According to an exemplary embodiment, a multimode power amplifier configured to receive an RF input signal and provide an RF output signal in linear and saturated operating modes includes an output stage configured to receive a fixed supply voltage and to provide the RF output signal. The multimode power amplifier further includes at least one driver stage coupled to the output stage, where the at least one driver stage is configured to receive the RF input signal and an adjustable supply voltage. The adjustable supply voltage controls an RF output power of the RF output signal when the multimode power amplifier is in the saturated operating mode. The at least one driver and the output stage are each biased by a low impedance voltage in the linear and saturated operating modes. The adjustable supply voltage can be controlled by a fixed control voltage in the linear operating mode.

Abstract: A power amplifier system includes a nonlinear power amplifier that receives a predistorted input signal. A receiver receives an output signal from the power amplifier and provides an observed signal. A bias controller provides a delayed dynamic bias signal to the power amplifier wherein the bias signal delay is dynamic and is a function of the observed signal for synchronizing the predistorted input signal with the dynamic bias signal. A method is also described that alternately adjusts predistortion delays and bias signal delays as a function of observed signals.

Abstract: An amplifier element amplifies RF signals. An emitter follower unit drives the amplifier element at a constant voltage corresponding to a reference voltage supplied to a reference terminal from outside. A current injection unit drives the amplifier element at a constant current corresponding to the reference voltage. An analog control unit analogically controls the output voltage of the emitter follower unit in correspondence with the control voltage supplied to a control terminal from outside. A mode switching unit switches whether the emitter follower unit is operated or not in correspondence with the control voltage.

Abstract: Aspects of a method and system for polar modulating QAM signals with discontinuous phase may include amplifying a signal via a plurality of amplifiers such that a combined gain of the plurality of amplifiers comprises a coarse amplitude gain and an amplitude offset gain. A gain of one or more of the plurality of amplifiers may be adjusted to set the coarse amplitude gain, and a gain of one or more remaining ones of the plurality of amplifiers may be adjusted to set the amplitude offset gain. The setting of the coarse amplitude gain and/or said amplitude offset gain may be adjusted dynamically and/or adaptively. The signal may be generated by phase-modulation of a radio-frequency carrier. The combined gain of the plurality of amplifiers may be controlled based on a desired amplitude modulation. The plurality of amplifiers may be integrated within an integrated circuit (IC) or chip.

Abstract: DC power savings in a mobile communication device can be achieved by dynamically adjusting the biasing for a receiver based on the communication link quality. The output signal levels of at least one low noise amplifier (LNA) are monitored to identify the DC operating conditions for the LNA. Closed loop control of the DC biasing is adjusted based on a comparison between the monitored DC operating conditions and a reference signal. The output of the LNA is also coupled to a radio receiver section that is configured (e.g., SW or HW) to evaluate the link quality based on various criteria such as inter-modulation distortion, noise, interference, fading, etc. The reference signal that is used to control the DC biasing of the LNA is adjusted (periodically, continuously, or on demand) in response to the evaluated link quality. The dynamic biasing yields acceptable signal reception with low DC power consumption.

Abstract: A low noise amplifier (LNA) circuit includes a linear input stage including a first circuit that generates an output current and has a low input impedance. A device receives an input signal, communicates with the low impedance input of the first circuit, and includes a variable resistor having a resistance that varies based on the input signal.

Abstract: In one implementation, a power amplifier may include a gain device to receive an input signal and to output an amplified signal, and a compensation device coupled to the gain device to compensate for a change in a capacitance of the gain device occurring due to a change in the input signal. The power amplifier may be formed using a complementary metal oxide semiconductor (CMOS) process.

Abstract: This invention provides an electronic part for high frequency power amplification (RF power module) which will automatically perform the precharge level setting for proper output power at start of transmission without requiring the software process for precharging to run on the baseband IC, which can reduce the burden on users, namely, mobile phone manufacturers. Such electronic part configured to amplify RF transmit signals includes an output power control circuit which supplies an output power control voltage to a bias control circuit in a high frequency power amplifier circuit, based on an output power level directive signal. This electronic part is equipped with a precharge circuit which raises the output power control voltage to produce a predetermined level of output power, while detecting a current flowing through a final-stage power amplifying element, triggered by rise of a supply voltage at start of transmission.

Abstract: Open-Loop RF Transmitter Output Power Control for Increased Power Efficiency (NC #98068) method includes determining a desired RF output power and obtaining a battery voltage value; determining a supply control voltage, a bias control voltage and a highest power efficiency; and transmitting selected values of the supply control voltage and the bias control voltage to supply control circuitry and bias control circuitry.

Abstract: A power management system is provided for a software-defined radio. The power management system includes: an antenna; a regulated power supply; a power amplifier; and a digital signal processor. A software-implemented power supply calculator and power supply adjustor are operable within the digital signal processor. The power supply calculator receives an indicator of a type of waveform to be transmitted by the radio and determines the drain voltage for the power amplifier based on the waveform indicator. The power supply adjustor receives forward power and reflected power values from the antenna and computes a voltage standing wave ratio (VSWR). The power supply adjustor further computes an adjustment for the drain voltage based on the VSWR.

Abstract: A technique to adjust gain and DC level of current DAC signals with offset to generate a voltage signal that is used to control power level of a power amplifier. One or more current mirrors from a set of current mirrors is programmably selected to set gain of a current-to-voltage conversion stage. A second set of current mirrors used to adjust DC level current is oppositely tracked to the current mirrors used for the gain. The opposite tracking allows for deactivation (or activation) of respective current mirrors in the second set in response to activation (or deactivation) of respective gain setting current mirrors to maintain a substantially constant DC level when gain values are changed. An additional set of current mirrors allows for independent compensation of DC offsets.

Abstract: A transconductance control circuit, comprising: a test transconductance circuit for providing an output current from a reference voltage; apparatus for deriving a bias current for the test transconductance circuit from the output current, the bias current including a component that varies with temperature and a component that varies with process; and apparatus for providing the bias current to other transconductance circuits.

Abstract: The present invention relates to a bias control circuit and method for supplying a bias signal to at least one stage of an amplifier circuit, wherein a dual bias control is provided by generating a bias current and additionally using this bias current to derive a control signal for limiting a supply voltage of the at least one amplifier stage in response to the control signal. Thereby, a compression of the output signal of the amplifier stage, which results from the voltage limitation, can be realized in addition to the base current steering. This leads to a decrease in small signal gain and thus reduced output noise.

Abstract: A variable gain amplifier has a first amplifier circuit (106) having a first field-effect transistor and amplifying a signal input to a gate of the first field-effect transistor to output; a gate bias control circuit (102) controlling a gate bias of the first amplifier circuit to control a gain of the first amplifier circuit; and a variable matching circuit (103) controlling a capacitor connected to the gate of the first amplifier circuit to control the gain of the first amplifier circuit.

Abstract: Dynamic biasing techniques are used to enhance both linearity and efficiency within a transistor power amplifier. In at least one embodiment, as the power level being processed by a transistor increases toward a saturation point, a transistor is moved from class B or class AB operation toward class A operation. This increases the linearity of operation (because class A operation is typically highly linear) without a corresponding decrease in efficiency (because efficiency typically peaks near saturation). Similarly, as the power level decreases from the saturation point, the transistor is moved from class A or class AB operation toward class B operation. This increases the efficiency (because class B operation is more efficient than class A or AB), while having little effect on linearity (because operation is moving away from saturation).

Abstract: The present invention provides dynamic biasing of transistor in an amplifier (1) comprising at least two interconnected transistor (10, 20) provided for processing an input signal. Once the input signal is applied to a driver transistor (10), a DC current signal of the output electrode (16) of this transistor (10) is detected. This DC current detection could be implemented as a detection of a voltage drop by providing the DC current signal to a resistor (130). A dynamic bias signal is then generated based on this detected DC current signal or voltage drop proportional to the DC current signal. The bias signal is applied to an input electrode (22) of a final transistor (20) for providing dynamic biasing thereof. The biasing of the invention reduces the intermodulation distortion of the final transistor (20) and amplifier (1). In addition, the biasing enables an automatic change of operation class for the transistor (20).

Abstract: A low noise amplifier for operating in response to different gain modes is disclosed. The low noise amplifier includes a voltage adjusting circuit, which provides a first bias voltage at a first gain mode and provides a second bias voltage at a second gain mode, where the second bias voltage is different from the first bias voltage; and an amplifying circuit coupled to the voltage adjusting circuit, for providing a first transfer characteristic according to the first bias voltage during the first gain mode in order to amplify an input signal to generate an output signal, and for providing a second transfer characteristic according to the second bias voltage during the second gain mode in order to amplify the input signal to generate the output signal.

Abstract: A method and apparatus is provided for use with a power amplifier to provide a regulated supply to the power amplifier. The invention uses a combination of voltage and current regulation to overcome the problems encountered in the prior art. In one example, voltage regulation is used at high power levels, while current regulation is used at low power levels.

Abstract: Aspects of a method and system for polar modulation with discontinuous phase for RF Transmitters with power control may include amplifying a signal via a plurality of amplifiers such that a combined gain of the plurality of amplifiers comprises a coarse amplitude gain, a power level gain and an amplitude offset gain. A gain of one or more of the plurality of amplifiers may be adjusted to set the coarse amplitude gain and the power level gain. A gain of one or more remaining ones of the plurality of amplifiers may be adjusted to set the amplitude offset gain. The setting of the coarse amplitude gain, the power level gain and/or the amplitude offset gain may be adjusted dynamically and/or adaptively.

Abstract: A radio frequency (RF) module provides first and second power amplifiers configured to produce first and second amplified RF signals at first and second output RF terminals, respectively; and first and second arrays of pads positioned opposite each other, the first array including the first output RF terminal and the second array including the second output RF terminal. The module also provides two reserve terminals that can be connected to capacitors, inductors, sensors for RF linearity, or can be left unconnected.

Abstract: A high-frequency circuit is provided. In the high-frequency circuit, a first PIN diode is provided in a signal line and a second PIN diode is provided between the signal line and ground so that an attenuating circuit is formed. A power supply is applied to one end of a series circuit composed of two resistors. The other end of the series circuit is connected to ground via a drain-source path of an FET. An AGC voltage is applied to a gate of the FET. A bias voltage in accordance with the AGC voltage is applied to a base voltage of a low-noise amplifier via the first and second PIN diodes so as t control attenuation of the first PIN diode and an operating current of the low-noise amplifier.

Abstract: The invention relates to a method and apparatus for shaping an input signal Son which is input to a multi-stage amplifier arrangement, to provide a definable output signal contour Soff. Individual amplifier stages are controlled by a control signal generated by a pulsed current source of a definable pulse length T. According to the invention, successive amplifier stages are each controlled (switched on) after a definable delay time ?ton 1, ?ton 2 following the preceding stage. Each amplifier stage has an assigned pulsed current source for generating the control signals of definable pulse length T. One such pulse generator respectively is assigned to each current source.

Abstract: A method and circuit system for improving power efficiency of RF power amplifiers is disclosed. A preferred embodiment comprises a power amplifier comprising: a plurality of amplifier stages, a power regulator providing an output supply voltage at an output node responsive to an adjustable power control signal, wherein the output supply voltage is applied to at least one stage of a power amplifier; and an amplifier biaser providing a bias signal corresponding to the adjustable power control signal, wherein the output supply voltage and the bias signal are independently generated as functions of the adjustable power control signal.

Abstract: A power amplifier for use in wireless communication devices is disclosed that reduces the noise generated at the output of the amplifier in the receive band of the wireless communication device. A resonant circuit is inserted between the base ballast resister and the lumped resister. The resonant frequency of the resonant circuit is adjusted to correspond to the frequency offset between the transmission frequency and the frequency corresponding to the peak noise in the receive band of the communication device.

Abstract: Power consumed by a power-variable amplifying unit for amplifying and supplying data to an antenna in a mobile telephone carrying out data transmission by changing transmission power in accordance with a TPC bit transmitted from a base transceiver station is reduced. The power-variable amplifying unit is constituted with a variable gain amplifier (21) in which a gain is variably controlled with a control voltage corresponding to the above-described TPC bit, a driver amplifier (22) with a fixed gain, and a power amplifier (23) with a fixed gain. Then, a variable resistance 25 for bypassing a current flowing through a transistor (26) of the driver amplifier (22) is provided, and a resistance value of this variable resistance (25) is variably controlled with the control voltage corresponding to the above-described TPC bit. Accordingly, a current quantity of the current flowing through the transistor 26 can be controlled to be a current quantity according to the control voltage (=transmission power).

Abstract: A radio frequency amplifier module (500) has a voltage monitor (546) that monitors an input supply voltage of an input power supply (534) and an adjustable power supply (512) that accepts power from the input power supply (534) and produces an adjustable power supply output that has a controllable voltage. The radio frequency amplifier module (500) further has an amplifier (402) that is supplied by the adjustable power supply output and that amplifies a radio frequency signal. The radio frequency amplifier module (500) also has an output controller (546) that is communicatively coupled to the voltage monitor and the adjustable power supply (512). The output controller (546) controls, in response to the input source voltage, the controllable voltage of the adjustable power supply output.

Abstract: A biasing circuit adapted for operative coupling to the first input terminal so as to provide a relatively high biasing impedance to ground at the first input terminal, said biasing circuit being adapted to controllably vary the DC-voltage signal which biases the transistor amplifier, whilst at least one component of the biasing circuit is configured to simultaneously form a low-pass circuit for filtering a noise component of the DC-voltage signal before the DC-voltage signal is provided to the first input terminal.

Abstract: A bias circuit includes a transistor having a control gate, a first terminal and a second terminal coupled to a ground level, a first resistor coupled to the control gate, a first capacitor coupled between an input signal and the first resistor, a diode coupled between a connection point of the first capacitor and the first resistor, and the ground level, a second capacitor coupled between the control gate and the ground level, a second resistor coupled between the control gate and the ground level, a third resistor coupled between the control gate and a predetermined voltage, a fourth resistor coupled between the predetermined voltage and the first terminal, and a fifth resistor coupled between the first terminal and a bias signal. A current through the transistor corresponds to the input signal, and the bias signal is generated according to the current through the transistor.

Abstract: A radio frequency circuit includes a radio frequency signal source which produces a radio frequency signal, a power amplifier which power amplifies the radio frequency signal from the radio frequency signal source, and a control unit which controls an output power of the power amplifier. Particularly, the control unit is configured to hold control data defining a relationship among an output power, a gain, and an operation bias point of the power amplifier and adjust the operation bias point of the power amplifier based on the control data such that the output power of the power amplifier is set into a level designated by an external power designating instruction.

Abstract: A monotonic variable gain amplifier which can be controlled to achieve a desired gain. The amplifier has: —at least two amplifier stages (41-45) connected in parallel between input and output terminals, each amplifier stage including: * a fixed gain transconductance amplifier (100, 102) through which a bias current (Ibi) flows controlled by the input signal,—a controllable current divider (104, 106) controllable to vary the ratio of the amount of the bias current (Ibi) that is drawn from a first output point to the amount (l1i) of the bias current that is drawn from a voltage source, and—a control loop (190) to keep a DC voltage combined with an outputted amplified DC current at a constant level.

Abstract: An emitter follower circuit applies to an input terminal of a second amplifying device a voltage according to a reference voltage applied to a reference terminal. First and second resistors are connected in series between the reference terminal and an input terminal of a first amplifying device. The collector of a first transistor is connected to the reference terminal and a control voltage is applied to the base of the first transistor. A third resistor is connected between the emitter of the first transistor and a grounding point. A current mirror circuit draws a current proportional to a current input from the collector of the first transistor from a connection point of the first and second resistors.

Abstract: A transmitter employing variable gain amplifiers and operating with both constant and nonconstant envelope modulation systems is contrived to suppress variation in the transmitting power when constant envelope modulation is performed. The transmitter comprises a PM loop, an AM loop, and a variable gain amplifier which is shared by the PM loop and the AM loop and combines phase information that the PM loop outputs and envelope information that the AM loop outputs by gain control. The variable gain amplifier comprises a variable gain amplifier body having a supply voltage terminal and a bias current detection terminal for extracting a bias current corresponding to a gain, wherein the gain changes with a change in the potential of the supply voltage terminal, and a bias control block connected to the supply voltage terminal and the bias current detection terminal.

Abstract: A transimpedance amplifier (TIA) circuit comprises an input and an amplifying stage that includes N amplifiers, that generates a first signal and that is AC coupled to the input. A bias stage generates a second signal and that is DC coupled to the input. An output stage is driven by the first signal from the amplifying stage and the second signal from the bias stage.

Abstract: A bias circuit for the wireless transceiver is disclosed, which can be used for modulating the gain of the amplifier. The bias circuit comprises a first stage bias unit for receiving a constant current, a control voltage, and a first reference voltage and outputting a first outputting current, wherein the control voltage is used for controlling the value of the first outputting current, and further, the first outputting current can be increased or decreased by representing as an analog form, thus, the gain of the amplifier can be modulated according to the first outputting current, and the modulation of the gain can be represented as an analog form, such that the transient response occurred while the gain is modulated can be reduced.