A semiconductor integrated circuit includes a first transmission power mode configured to transmit by a first power, and a second transmission power mode configured to transmit by a second power smaller than the first power, the semiconductor integrated circuit. The semiconductor integrated circuit includes a first transistor configured to receive and amplify a transmission signal in the second transmission power mode, and an attenuator including a resistor element and a switching element, provided between an output of the first transistor and an output terminal, configured to control attenuation of an output signal of the first transistor.

Disclosed is an envelope tracking (ET) system having a transmit (TX) section, a power amplifier (PA), a fast switched-mode power supply (Fast SMPS), and control circuitry. The TX section receives an input signal and provides a modulated signal to the PA. The TX section also generates an ET signal based on a modulation envelope of the modulated signal. The TX section provides an envelope control (EC) signal based on the ET signal to modulate a supply signal provided to the PA by the Fast SMPS. The control circuitry provides a transmit TX gain signal and an ET gain signal to the TX section based on a PA temperature signal, a TX temperature signal, a target power signal, a measured power signal. The control circuitry is configured to maintain the efficiency and linearity of the PA over a wide operating temperature range.

One or more example relate, generally, to generating radio frequency (RF) signals. An apparatus may include a signal generator, an amplification stage, and a feedback control loop. The signal generator may generate a pulsed radio frequency (RF) signal at least partially responsive to a digital pulsed waveform defined by one or more commands. The amplification stage may amplify the pulsed RF signal. The feedback control loop may be coupled to the amplification stage to regulate a power level of respective steps of the pulsed RF signal.

An amplifier according to an embodiment of the present invention includes a first transistor and a second transistor that are connected between a ground point and a power supply. A control terminal of the first transistor is connected to an input terminal. A first terminal of the first transistor is connected to the ground point. A second terminal of the second transistor is connected to an output terminal. The amplifier further includes an impedance element and a variable resistance unit. The impedance element is connected between the second terminal of the second transistor and the power supply. The variable resistance unit is connected between the second terminal of the first transistor and the first terminal of the second transistor.

The invention discloses a transmitter comprising a pulse encoder for creating pulses from the amplitude of an input signal to the transmitter, a compensation signal generator for cancelling quantization noise caused by the pulse encoder, a mixer or I/Q modulator for mixing an output of the pulse encoder with the phase of an input signal to the transmitter, said output of the pulse encoder comprising the amplitude of the complex input signal plus the quantization noise caused by the pulse encoder, and an amplifier for creating an output signal from the transmitter. In the transmitter, a control signal (C.sub.A) for controlling a function of the amplifier comprises an output signal from the compensation signal generator, and an input signal to the amplifier comprises an output from the mixer having been modulated to a desired frequency.

The embodiments herein relate to a method in a first network node (301) for handling Automatic Gain Control, AGC, scaling and Transmit Power Control, TPC, scaling of a signal received from a second network node (305). The first network node AGC compensates the signal for any AGC scaling changes. The AGC compensating the signal results in an AGC compensated signal comprising a constant AGC scaling. The first network node detects a TPC scaling change of the signal. The detection is based on the signal after the TPC scaling change and based on a predicted channel estimate. The predicted channel estimate is based on the signal before the TPC scaling change. The first network node TPC compensates for the detected TPC scaling change. The TPC compensation results in an AGC and TPC compensated signal comprising the constant AGC scaling and a constant TPC scaling according to the detected TPC scaling change.

A power amplifier module including an input configured to receive an input radio frequency signal, the input radio-frequency signal including a series of data symbols, an output configured to provide an output radio-frequency signal, a power amplifier having a signal input to receive the input radio-frequency signal and a power supply input to receive a supply voltage, the power amplifier configured to amplify the input radio-frequency signal to provide the output radio-frequency signal, and a controller to receive an indication of a peak output power level of an upcoming data symbol in the series of data symbols, to adjust at least the supply voltage provided to the power amplifier based on the peak output power level of the upcoming data symbol, and to configure the power amplifier module to maintain a substantially constant gain over the series of data symbols.

A digital microwave radio system includes a splitter that splits a common baseband input into two baseband outputs, first and second transmitters, each transmitter electrically connected to a baseband output of the splitter via a mixer, a common local oscillator electrically connected to the mixer of the first transmitter and the mixer of the second transmitter via an adjustable phase shifter, respectively, and a combiner. The common local oscillator is configured to up-convert each baseband output into a radio-frequency signal using a corresponding mixer. The combiner combines the two radio-frequency signals into a 0-degree phase-shift output and a 180-degree phase-shift output, respectively. A phase error control loop adjusts the phase shifter to minimize the 180-degree phase-shift radio-frequency output. A combiner gain control loop adjusts the output power level of the two transmitters in accordance with an actual power detector reading at the 0-degree phase-shift radio-frequency output.

A method of characterizing an envelope tracking amplification stage, the method comprising: generating an input test waveform which is representative of an input waveform under normal operating conditions of the amplification stage; applying a respective one of a plurality of different shaping functions, each comprising a non-linear transfer function, to the input signal envelope in each of a plurality of test periods during the period in which the input test waveform is applied as the input signal to generate the input to the envelope tracking modulated supply voltage; measuring parameters of the amplification stage during the period in which the input test waveform is applied in order to allow determination of the gain, phase and efficiency characteristics of the amplifier; and for each of the gain, phase and efficiency characteristics, generating a three dimensional plot of the characteristic with respect to input power and supply voltage applied to the amplifier.

A technology related to a power amplifier used in a wireless communication circuit is disclosed. A radio frequency (RF) power amplifier includes a plurality of unit differential amplifiers of which inputs are connected to a common input terminal and outputs are connected to a common adder, and having a gain of a weight of a corresponding bit of a binary gain control word. Each of the differential amplifiers may be configured as a complementary metal-oxide semiconductor (CMOS) differential cascode amplifier. In addition, the RF power amplifier may include a structure in which a plurality of attenuators of the same structure are cascade-connected so that an attenuation rate may be linearly and digitally controlled and an output of each attenuator is connected to an output adder through differential buffers of which turn-on and turn-off are controlled by a controller.