Abstract: An amplifier circuit of envelope tracking scheme has a timing adjusting unit having a finite number of adjustment values for adjusting time by which the output is delayed from the input, and capable of adjusting a time difference between an input signal and a power supply voltage which reach an amplifier, by making a selection from the adjustment values; a test signal output unit capable of repeatedly sending out a test signal serving as the input signal at predetermined cycles; and an adjustment value determining unit sequentially measuring output power for m (?k) periods from the amplifier while changing an adjustment value of the timing adjusting unit to a different value every k periods of the test signal, searching for an adjustment value at which a total sum of the output power form periods is maximum, and setting the adjustment value on the timing adjusting unit.

Abstract: An integrated circuit for providing a differential interface for an envelope tracking signal is described. The integrated circuit includes a subtraction module having a first input for receiving a digital envelope tracking signal and a second input for receiving a second signal, wherein the subtraction module is arranged to subtract the second signal from the digital envelope tracking signal and produce an envelope tracking signal with a reduced average direct current (DC) component; a digital-to-analog converter (DAC) arranged to receive the envelope tracking signal with the reduced average DC component and produce a differential analog version thereof; and a modulator operably coupled to a differential output of the DAC, wherein the modulator comprises a DC input point arranged to insert a DC component into the differential analog version of the envelope tracking signal.

Abstract: There is disclosed a multi-stage amplifier comprising: a first amplifier stage; a second amplifier stage; a first voltage supply stage arranged to provide a supply voltage to the first amplifier in dependence on an average power of a signal to be amplified; and a second voltage supply stage arranged to provide a supply voltage to the second amplifier in dependence on an instantaneous power of a signal to be amplified.

Abstract: A distortion compensation device includes a distortion compensator that predistorts an input signal based on delay signals and distortion compensation coefficients corresponding to the respective delay signals obtained by applying different amounts of delay to the input signal, a calculator that calculates an error signal based on the predistorted input signal and an output signal from an amplifier that amplifies the predistorted input signal, a calculator that calculates prospective distortion compensation coefficients for updating the distortion compensation coefficients, based on the error signal, a saturation processor that performs saturation processing for bringing, when the prospective distortion compensation coefficients do not fall into a preset range, the prospective distortion compensation coefficients into the preset range, and a controller that controls the updating of the distortion compensation coefficients based on pieces of coefficient saturation information indicating whether the saturation

Abstract: Provided is a transmission circuit that operates highly efficiently by avoiding deterioration of the linearity of an output signal and suppressing occurrence of distortion of the output signal, when using the envelope tracking method. In this transmission circuit, offset control section (160) sets voltage that makes the corrected envelope signal level equal to or higher than the delayed envelope signal level, as offset voltage. By this means, the corrected envelope signal level becomes equal to or higher than the delayed envelope signal level, so that it is possible to prevent the power supply voltage from being lower than the optimal power supply voltage, making it possible to prevent the linearity of an output signal from deteriorating in power amplifier (130).

Abstract: The invention is based on the fact that the current output from a DDB controlled amplifier in backoff, i.e. for low amplitudes, is reduced more or less linearly with the amplitude of the signal to be amplified. Therefore, it is enough to use smaller amplifiers which are able to output the necessary RF current. Hence, according to the present invention, the total DDB amplifier is divided into smaller parts that are coupled to the output only when needed.

Abstract: A digital pre-distortion (DPD) power amplifying apparatus and a method for digitally controlling synchronization of the DPD power amplifying apparatus, which includes a power amplifier, a bias shifter and a DPD unit, are provided. The method includes acquiring a DPD path delay time at a path along which an input signal is fed back to the DPD unit; delaying an input signal incoming to the power amplifier by the DPD path delay time and acquiring synchronization by delaying a bias signal a predetermined number of times until the bias signal and the delayed input signal are synchronized with each other; and in response to synchronization between the bias signal and the delayed input signal being established, pre-distorting the input signal according to a feedback signal output from the power amplifier.

Abstract: A transmitter (50) includes a nonlinear predistorter (58) having two instances of an inverting transform (106, 106?) that may be implemented in a look-up table (122) and that implements a transform which is the inverse of an average terms component (96) of a nonlinear transform model (94) for an amplifier (70). The look-up table (122) may be updated using a continuous process control loop that avoids Cartesian to polar coordinate conversions. One of the two instances of the inverting transform (106) is cascaded with a non-inversing transform (108) within a residual cancellation section (110) of the predistorter (58). The non-inversing transform (108) implements a transform which is an estimate of a deviation terms component (98) of the nonlinear transform model (94). The residual cancellation section (110) produces a weak signal that replaces an unwanted residual term in an amplified communication signal (76) with a much weaker residual term.

Abstract: An apparatus and a method for expanding an operation region in an envelope tracking power amplifier are provided. The apparatus for amplifying power of a transmission signal includes an amplitude component determination unit, a supply modulator, and a power amplify module. The amplitude component determination unit determines an amplitude component of a transmission signal. The supply modulator generates a supply voltage to be provided to the power amplify module depending on the amplitude component of the transmission signal determined by the amplitude component determination unit. The power amplify module amplifies power of the transmission signal depending on the supply voltage generated by the supply modulator.

Abstract: An adjustable gain audio power amplifying circuit includes an input unit, an audio amplifying unit connected to the input unit, a gain adjusting unit connected to the audio amplifying unit, a controlling unit connected to the gain adjusting unit, a comparing unit connected between the gain adjusting unit and the controlling unit and an output unit connected to the audio amplifying unit. The comparing unit compares an outputted signal of the output unit with a common-mode reference voltage, outputs a gain adjustment controlling signal and sends the gain adjustment controlling signal into the controlling unit. When the outputted signal equals the common-mode reference voltage, the gain adjustment controlling signal turns over and then the controlling unit detects the turnover and sends a received gain adjustment signal into the gain adjusting unit. Based on the received gain adjustment signal, the gain adjusting unit controls gains of the adjustable gain audio power amplifying circuit.

Abstract: To provide an envelope tracking type amplifier that has high efficiency and small fluctuations, an output unit supplies an output signal that is adjusted corresponding to an input signal to a power supply terminal of the amplifier. The output unit includes an analog amplifying circuit that amplifies the input signal; a digital circuit that selectively outputs a first voltage or a second voltage that is lower than the first voltage; and first and second output circuits. The first output circuit includes a first integrating circuit that integrates an output signal of the digital circuit; and a combining section that combines an output signal of the first integrating circuit and an output signal of the analog amplifying circuit and outputs the combined signal to a power supply terminal of the amplifier.

Abstract: An amplifier circuit includes an amplifier and a noise suppression block. The amplifier is arranged for receiving an input signal at an input port and generating an output signal at an output port according to the input signal. The noise suppression block is coupled between the input port and the output port of the amplifier, and arranged for receiving the input signal and the output signal and applying noise suppression to the output signal generated from the amplifier according to the received input signal and the received output signal.

Abstract: There is provided a power amplifier which may suppress fluctuations in a phase of an output signal in accordance with fluctuations in a level of an input signal by varying an impedance between a signal input terminal and an amplification unit in accordance with a power level of an input signal. The power amplifier includes a bias voltage generation unit generating a bias voltage set in accordance with a power level of an input signal, an amplification unit amplifying the power level of the input signal in accordance with the bias voltage, and an impedance variation unit varying an impedance of a signal transmission path through which the input signal is transmitted to the amplification unit in accordance with the bias voltage.

Abstract: An integrated circuit for transmit and receive matching is described. The integrated circuit includes a transmit amplifier. The transmit amplifier includes a first transistor, a second transistor and a first inductor. The first inductor couples the first transistor to the second transistor. The integrated circuit also includes a low noise amplifier. The low noise amplifier includes a third transistor, a fourth transistor, the first inductor, a second inductor, a third inductor and a transformer. The second inductor couples the first inductor to the third transistor. The third inductor couples the third transistor to ground.

Abstract: A variable gain amplifier circuit includes output nodes, a plurality of amplifiers, and a detection circuit. The amplifiers are coupled in parallel with each other between the output nodes and a reference node and selectively assume an operating state in accordance with a control signal. The detection circuit outputs a detection signal according to the magnitude of an input signal to each amplifier. Each amplifier includes a first transistor, a second transistor, and a bias circuit. The first transistor receives, at its control electrode, the input signal or a signal proportional to the input signal. The second transistor is series-coupled to the first transistor between the first reference node and an output node. The bias circuit applies a DC voltage of a magnitude according to the detection signal to a control electrode of the second transistor.

Abstract: The present invention relates to a voltage variable type digital audio amplifying device for noise compensation and a method therefor, and more specifically, varies the power according to an audio input signal, and compensates for the noise generated when varying the power, thereby enhancing audio output efficiency and easily removing noise.

Abstract: A data receiver, a method of operating a data receiver, and an integrated coupling system in a data receiver are disclosed. In one embodiment, the data receiver comprises an input terminal for receiving an input data signal, an input amplifier for amplifying selected components of the input data signal, and an input signal path for transmitting specified high-frequency components and a baseline component of the input data signal from the input terminal to the input amplifier. The data receiver further comprises a feed-forward resistive network connected to the input terminal and to the input amplifier. This feed forward resistive network is used to forward a low-frequency drift compensation signal from the input terminal to the input amplifier, using a passive resistive network, to compensate for low frequency variations in the input data signal, and to develop a desired bias voltage at the input amplifier.

Abstract: An automatic gain controller is disclosed. The AGC includes an input for monitoring a signal associated with an amplifier and a gain control circuit for controlling the gain of the amplifier in response to the monitored signal, wherein the gain control circuit is adapted to control the gain of the amplifier in accordance with a gain control function having continuously variable attack and release time constants, both of which depend on the amplitude of the monitored signal.

Abstract: A linear RF transmitter (100) includes a forward path including a baseband signal combiner (109) and an RF (radio frequency) power amplifier (123), and a linearizing control loop from an output (127) of the RF power amplifier to an input of the combiner (109). A feedback control path (105, 107) of the loop delivers a baseband error control signal to the combiner. The transmitter further includes a test signal generator (102) to apply to the combiner in a closed loop level training mode a test signal comprising a voltage Vin which increases with time in a non-linear manner approaching an asymptotic limit such that in response an output signal produced by the combiner is a voltage Ve which is substantially constant over a period of time.

Abstract: Apparatus and methods for biasing a power amplifier are disclosed. In one embodiment, a power amplifier system includes a power amplifier configured to amplify a radio frequency (RF) signal and a bias control circuit for generating a bias current for the power amplifier. The bias control circuit is configured to receive an envelope of the RF signal and to change an amplitude of the bias current based at least in part on the envelope.

Abstract: There is provided an amplification stage comprising: an input scaling block for scaling an input signal in dependence on an input scaling factor to generate a scaled version of the input signal; a power amplifier for generating an amplified version of the scaled input signal; an envelope detector for generating a signal representing the envelope of the input signal; an envelope scaling block for scaling the envelope signal in dependence on an envelope scaling factor to generate a scaled version of the envelope signal; a non-linear mapping block for generating a voltage representative of the supply voltage in dependence on the scaled envelope signal; a modulator for generating a power supply voltage for the amplifier in dependence on the voltage generated by the non-linear mapping block; and a power control block for maintaining a linear relationship between the envelope scaling factor and the input scaling factor.

Abstract: A distortion compensation apparatus includes a distortion compensation signal generation unit that performs, on a transmission signal, distortion compensation processing using a series operation; a coefficient updating unit that updates series operation coefficients used for the series operation based on a feedback signal of a power amplification output which is output through power amplification processing of a distortion compensation signal output from the distortion compensation signal generation unit, and based on the distortion compensation signal; a memory that stores the distortion compensation signal corresponding to a transmission signal having a given power value and the feedback signal of the power amplification output as restraint information; and a control unit that performs control so that, in accordance with the power value of the transmission signal, restraint information corresponding to a power value different from the power value of the transmission signal is read and used for updating the

Abstract: An amplifying apparatus includes a first amplifier that amplifies an input signal on the basis of a value of a drain voltage and outputs a transmission signal, a distortion compensator that corrects a power amplitude of the input signal on the basis of a difference in power amplitude between the input signal and the transmission signal outputted from the first amplifier, a drain voltage controller that generates the drain voltage on the basis of the power amplitude of the input signal to be corrected, and a drain voltage corrector that corrects the drain voltage on the basis of the difference.

Abstract: Apparatus and methods are disclosed, such as those involving a receiver device. One such apparatus includes an equalizer configured to process an input signal transmitted over a channel. The equalizer can include a programmable gain amplifier (PGA) block which includes an input node configured to receive the input signal; an output node; and a programmable gain amplifier (PGA). The PGA amplifies the input signal with an adjustable gain. The PGA block also includes a gain control block having an input electrically coupled to the input node. The gain control block is configured to adjust the gain of the PGA at least partly in response to the input signal from the input node such that the PGA generates an output signal with a substantially constant amplitude envelope to the output node.

Abstract: An amplification device that amplifies a signal, the amplification device includes an amplification unit that amplifies the signal using supplied power, a variable power supply unit that changes the power supplied to the amplification unit in accordance with an envelope of the signal, a radiation unit that radiates light onto the amplification unit, and a control unit that controls the light to be emitted from the radiation unit in accordance with slope of the envelope of the signal.

Abstract: A signal amplifying circuit is provided. The signal amplifying circuit includes a signal amplifier and a control circuit. The control circuit includes a compare unit and a register unit. The compare unit compares an input signal of the signal amplifier with a reference signal to generate a compare signal. The register unit receives and registers a control signal to be transmitted to the signal amplifier, and provides a registered signal to the signal amplifier according to the registered control signal when the compare signal is changed.

Abstract: An amplifying device which amplifies a signal, includes: an amplifier which amplifies an input signal by a power supplied from a power node; a first power source which supplies a fixed voltage to the power node; a second power source which supplies a variable voltage to the power node based on an envelope signal relating to the input signal and voltage of the power node; an active short device which reduces impedance of the power node when the first power source supplies the power to the power node and the second power source does not supply the power to the power node; a synthesizer which synthesizes the envelope signal and a cancel signal so that the second power source does not supply the power to the power node according to voltage variation of the power node by the active short device.

Abstract: The invention relates to a method for amplifying a carrier signal (CS1) by using a power amplifier (PA1), the power amplifier (PA1) is feed with a supply voltage (PASV1) of a power supply (SMPS1). The method comprises the step of adapting a value of the supply voltage (PASV1) to a value related to a mean signal power of an input signal (DS) of a power amplifier system (PAS1).

Abstract: A transmission circuit adjust a difference between signal delay amounts in an amplitude path and a phase path with a low power consumption. An amplitude modulation section amplitude-modulates a phase modulation signal outputted from a phase modulation section with a voltage control signal provided by a regulator to generate a transmission signal for an output of an antenna. Similarly, a feedback signal generation section amplitude-modulates the phase modulation signal with a voltage control signal to generate a feedback signal. The signal is fed back to a delay adjustments sections used for calculating and adjusting the difference between the signal delay amounts in the amplitude path and the phase path. The feedback signal generation section is attained by a power amplifier having the same configuration as the amplitude modulation section and a smaller circuit scale.

Abstract: There is disclosed a method for determining the timing misalignment between a power supply and an output in an envelope tracking amplification stage, the method including the steps of: estimating a distortion parameter in the amplification stage; and determining a timing error in dependence on the estimated distortion parameter.

Abstract: An envelope amplifier includes an amplifier unit, a comparator unit and an output unit. The amplifier unit is made up of a first output section that outputs a first current in response to an amplitude of an input envelope signal, and a second output section. The second output section outputs a second current of a current value proportionate to a current value of the first current. Absolute value of the current value of the second current is greater than that of a current value of the first current. Comparator unit compares the current value of the first current. The output unit sums a current via an inductor derived from a current sustained or broken in response to a compared result of the comparator unit to the second current to deliver the resulting sum current at an output end. The first current is configured to be terminated without being delivered to the output unit (FIG. 1).

Abstract: A mobile wireless communications device may include a portable housing, and a supply modulator carried by the portable housing. The supply modulator may include an output node, a linear amplifier coupled to the output node, and a switching amplifier also coupled to the output node. The switching amplifier may include at least one sensing transistor configured to sense current output from the linear amplifier and generate a drive voltage, and a hysteretic comparator coupled to the at least one sensing transistor and configured to be driven by the drive voltage. The mobile wireless communications device may also include a radio frequency (RF) power amplifier coupled to the output node of the supply modulator, and a wireless transceiver carried by the portable housing and coupled to the RF power amplifier.

Abstract: An amplifier includes an envelope detection unit that detects an envelope of a transmission signal; a comparing unit that compares a voltage of the envelope with a reference voltage; a selecting unit that selects, in accordance with a comparison result obtained by the comparing unit, an amplifying element that amplifies the transmission signal from among a plurality of amplifying elements each having different operating power; a voltage control unit that controls, in accordance with the envelope, a voltage that is used to amplify the transmission signal in the amplifying element that is selected by the selecting unit; a current measuring unit that measures a current of a power supply that supplies the voltage that is controlled by the voltage control unit; and a reference voltage control unit that controls the reference voltage such that the current measured by the current measuring unit decreases.

Abstract: A multi-channel receiver (200) comprises: an input (111) for receiving a wideband signal potentially comprising multiple channels, a tuner stage (110), a wideband amplifier (201) connected between the input (111) and the tuner (110), a controllable switch (202) bridging the amplifier (201) and a switch controller (203) designed to generate a switch control signal (BSC). For controlling the switch, the switch controller (203) is designed to measure at least one signal quality parameter and to generate its switch control signal (BSC) on the basis of the measured parameter. The decision of switching the switch (202) to its open state (amplifier active) is exclusively taken during at least one time interval when the receiver is switched to a channel.

Abstract: An integrated circuit for providing a differential interface for an envelope tracking signal is described. The integrated circuit includes a subtraction module having a first input for receiving a digital envelope tracking signal and a second input for receiving a second signal, wherein the subtraction module is arranged to subtract the second signal from the digital envelope tracking signal and produce an envelope tracking signal with a reduced average direct current (DC) component; a digital-to-analog converter (DAC) arranged to receive the envelope tracking signal with the reduced average DC component and produce a differential analog version thereof; and a modulator operably coupled to a differential output of the DAC, wherein the modulator comprises a DC input point arranged to insert a DC component into the differential analog version of the envelope tracking signal.

Abstract: A radio frequency amplifier amplifies a modulation signal or its phase modulation component and outputs the resultant signal. A linear amplifier adds an output voltage to a power supply voltage supplied to the radio frequency amplifier, amplifies a difference between the output voltage and the amplitude modulation component, and outputs the resultant difference. A control signal generation section detects a direction in which an output current of the linear amplifying section flows and generates a pulse modulation signal according to the direction of the current. A switching amplifying section controls connection and disconnection of a DC current based on the pulse modulation signal as a control signal so as to perform switching amplification for an output signal of the linear amplifying section, add the resultant signal to a predetermined DC voltage, and supply the resultant signal as the power supply voltage to the radio frequency amplifier.

Abstract: There is provided a power amplifier which may suppress fluctuations in a phase of an output signal in accordance with fluctuations in a level of an input signal by varying an impedance between a signal input terminal and an amplification unit in accordance with a power level of an input signal. The power amplifier includes a bias voltage generation unit generating a bias voltage set in accordance with a power level of an input signal, an amplification unit amplifying the power level of the input signal in accordance with the bias voltage, and an impedance variation unit varying an impedance of a signal transmission path through which the input signal is transmitted to the amplification unit in accordance with the bias voltage.

Abstract: An apparatus comprising an input, a control signal generator coupled to the input and having a control signal generator output, and an amplifier coupled to the control signal generator output, wherein a voltage supplied to the amplifier is switched based on the control signal generator output, and wherein the control signal generator output is based on a data signal in the input. Also included is an apparatus comprising circuitry configured to implement a method comprising detecting an incoming signal, calculating a derivative of the incoming signal, estimating a future incoming signal based on the derivative of the incoming signal and a time step, and providing the estimated future incoming signal to switch between a first supply voltage and a second supply voltage prior to or concurrent with an arrival of the future incoming signal at the switch, wherein the incoming signal and the future incoming signal are analog signals.

Abstract: The predistorter may include: a predistortion filter predistorting an input signal to provide an output signal; a predistortion output estimation unit estimating the characteristics of a nonlinear device based on a signal processed by the nonlinear device and the output signal, and calculating a desired output signal of the predistortion filter by using the estimated characteristics of the nonlinear device; and an adaptive algorithm driving unit comparing the output signal with the desired output signal to output an error as a comparison result, calculating a filter coefficient according to which the calculated error is minimized, and providing the calculated filter coefficient to the predistortion filter in order to update a filter coefficient of the predistortion filter.

Abstract: Embodiments of the present invention enable a blended control approach to generate a desired output waveform in an outphasing-based system. Embodiments of blended control according to the present invention combine outphasing with bias and/or amplitude control to yield an accurate, practical, and producible system with substantially comparable performance to that of a theoretical ideal outphasing system, but without the isolation and accuracy requirements of outphasing alone.

Abstract: The present invention relates to a power supply control network of an amplifying active elements system enabling at least one control signal to be transmitted to N different control systems of the power supply voltage of P different composed active amplifying elements. It comprises a set of distributor elements of power supply control signals connected in cascade.

Abstract: The invention refers to a Doherty power amplifier comprising a first power amplifier (Main PA) adapted to receive an input signal and adapted to provide a first output signal which is phase shifted with respect to the input signal. The amplifier further comprises a second power amplifier (Peak PA), adapted to receive a phase shifted input signal and adapted to provide a second output signal. The power amplifier is characterized in that at least one of the first or the second power amplifiers comprises a first driver power amplifier (T1) comprising a first gate input and a first drain output. The first driver power amplifier (T1) is coupled to a first output power amplifier (T2) comprising a second gate input and a second drain output. The first gate input and the second gate input are adapted to receive a control signal, the control signal being obtained after an envelope detection provided by an envelope detector coupled to the input signal.

Abstract: A system and a method are provided. The system may include (A) a measurement circuit arranged to measure at least a current power level of the input signal; (B) multiple non-linear power amplifiers; wherein different non-linear power amplifiers are associated with different power ranges; (C) a control circuit arranged to: (a) select at least one selected non-linear power amplifier to be used to amplify a second signal based on at least: (i) the current power level of an input signal; (ii) an association between the different power ranges and the different non-linear power amplifiers; (iii) an identity of at least one previously selected non-linear power amplifier; and (b) assist in an activation of the at least one selected non-linear power amplifier; and (D) a signal processing module, configured to process the input signal to provide the second signal such as to at least partially compensate for a non-linearity of each of the at least one selected non-linear power amplifier.

Abstract: There is provided a power amplifier capable of supplying variable bias to an amplifier circuit by accurately transferring the envelope components of an input signal during the supply of active bias power to the amplifier circuit. The power amplifier includes: an envelope detector detecting an envelope of an input signal; a bias power generator including at least one P-type MOSFET and one N-type MOSFET connected to each other in an inverter manner between a driving power terminal supplying driving power having a preset voltage level and a reference bias power terminal supplying preset reference bias power to generate bias power varied according to detection results from the envelope detector; and an amplifier amplifying the input signal according to the bias power level from the bias power generator.

Abstract: A power amplifier according to the present invention includes: a carrier amplifier (2) that amplifies a carrier of a high-frequency input signal; a peak amplifier (3) that amplifies a peak component of the high-frequency input signal; an average power level detecting circuit (11) that detects an average power level of the high-frequency input signal; a peak power level detecting circuit (12) that detects a peak power level of the high-frequency input signal; a first voltage controller (10a) that controls a DC voltage supplied to the carrier amplifier (2) according to an output voltage signal from the average power level detecting circuit (11); and a second voltage controller (10b) that controls a DC voltage supplied to the peak amplifier (3) according to an output voltage signal from the peak power level detecting circuit (12).

Abstract: A rail-to-rail buffer receiving a differential input signal and generating a differential output signal includes first and second amplifier circuits configured in a pseudo differential buffer structure and first and second comparators coupled to compare the respective part of the differential input signal and a first voltage and to generate select signals. Each of the first and second amplifier circuits includes first and second complementary differential input stages and the first and second comparators generate respective select signals to turn on only one of the first or the second differential input stage in each amplifier circuit depending on a value of the respective part of the differential input signal. In operation, the first and second complementary differential input stages of each amplifier circuit not being turned on at the same time.

Abstract: A digital power amplifier is disclosed. The digital power amplifier may comprise an amplifying stage configured for applying a first level of attenuation to an RF input signal in response to a desired output power level of the digital power amplifier; a reference loop configured for determining an average power of a sample of the RF input signal and providing a reference value at least partially based upon the average power of the sample of the RF input signal; a feedback loop configured for applying a second level of attenuation to a sample of an output of the amplifying stage and providing a feedback value indicating an average power of the attenuated sample of the output; and an error amplifier configured for providing a gain control adjustment signal to the amplifying stage, the gain control adjustment signal being determined based upon the reference value and the feedback value.

Abstract: A high frequency power amplifier maintains an excellent linearity regardless of a fluctuation of a load impedance and is downsized. The high frequency power amplifier detects an AC voltage amplitude at an output terminal of a final amplification stage transistor, and suppresses an input signal amplitude of a power amplifier when the voltage amplitude exceeds a predetermined threshold value.

Abstract: The invention is a method of transmitting a radio signal using a complex envelope elimination and restoration technique. The method includes receiving a radio frequency (RF) signal. Further, the method includes separating the RF signal into an in-phase baseband signal (I) and a quadrature baseband signal (Q). Still further, the method includes decomposing the (I) signal into a in-phase magnitude component and a in-phase phase component while decomposing the Q signal into a quadrature magnitude component and a quadrature phase component. Alternatively, the source signal could be digital baseband information. Digital signal processing could generate the phase and magnitude reference signals for the system.

Abstract: An audio amplifier circuit has a first cascode stage configured as a voltage gain stage and having an input for an audio signal, and an output. The circuit has a second cascode stage configured as a unity gain or near unity gain stage and having an input to receive an output from the first cascode stage, and a low impedance output to drive an output stage of an audio power amplifier. The first cascode stage has a first, input transistor having an input biased to a predetermined bias voltage, and a second, output transistor arranged to drive the second cascode stage. The first, input transistor of the first cascode stage may have a common-emitter configuration, and the second, output transistor may have a common-base configuration. The invention extends to an audio amplifier which includes a circuit of the invention.