Embodiments of radio frequency (RF) systems include a transmit/receive switch integrated with one or more power amplifiers and/or other components. The power amplifiers can have transformer-based architectures. A compensation circuit can act to protect the receive path during an RF transmit mode.

A Doherty amplifier is able to enhance efficiency in low-power and high-power RF communication states by enabling carrier and peaking amplifiers as required, and controlling bias modulation, depending on traffic loading levels in each of a set of consecutive communications timeslots. For example, if, in a low-power state, traffic loading levels do not exceed a relatively lower threshold in a communications timeslot, carrier amplifiers are selectively enabled as needed, peaking amplifiers are not enabled, and carrier amplifier bias levels are kept substantially constant. If, in an intermediate-power state, the lower threshold is exceeded but a relatively higher threshold is not exceeded, all carrier amplifiers are enabled, peaking amplifiers are selectively enabled, and bias levels are kept substantially constant. If, in a high-power state, the higher threshold is exceeded, all carrier and peaking amplifiers can be enabled, and the peaking amplifier bias tracks the RF envelope of the received RF signal.

Circuitry that includes a radio frequency (RF) power amplifier (PA) and a dynamic supply boosting circuit, is disclosed. The RF PA receives and amplifies an RF input signal to provide an RF transmit signal using a PA power supply voltage. The dynamic supply boosting circuit provides the PA power supply voltage using a dynamic supply input voltage, wherein when a peak-to-average (PAR) of the RF input signal exceeds a PAR threshold, the dynamic supply boosting circuit boosts the PA power supply voltage, such that the PA power supply voltage is greater than the dynamic supply input voltage.

Envelope-tracking control techniques are disclosed for highly-efficient radio frequency (RF) power amplifiers. In some cases, a III-V semiconductor material (e.g., GaN or other group III material-nitride (III-N) compounds) MOSFET including a high-k gate dielectric may be used to achieve such highly-efficient RF power amplifiers. The use of a high-k gate dielectric can help to ensure low gate leakage and provide high input impedance for RF power amplifiers. Such high input impedance enables the use of envelope-tracking control techniques that include gate voltage (Vg) modulation of the III-V MOSFET used for the RF power amplifier. In such cases, being able to modulate Vg of the RF power amplifier using, for example, a voltage regulator, can result in double-digit percentage gains in power-added efficiency (PAE). In some instances, the techniques may simultaneously utilize envelope-tracking control techniques that include drain voltage (Vd) modulation of the III-V MOSFET used for the RF power amplifier.

A multi-stage radio frequency power amplifier (RFPA) includes an output stage SMPA and a driver stage SMPA. As the multi-stage RFPA operates, the magnitude of an RF switch drive signal generated by the driver stage SMPA is dynamically minimized based on I-V characteristic curves of the output stage SMPA's power transistor and the output stage SMPA's dynamically changing load line. By constraining the magnitude of the RF switch drive signal as the multi-stage RFPA operates, VGS feedthrough of the RF switch drive signal is minimized, to the extent possible. Amplitude distortion and phase distortion in the RF output that might occur due to unconstrained VGS feedthrough, particularly at low output RF power levels, are therefore avoided. Operating all stages of the multi-stage RFPA in switch mode also results in high energy efficiency and an output RF spectrum with very low wideband noise (WBN).

An envelope-tracking current bias circuit includes a first rectifying circuit, a second rectifying circuit, and a first arithmetic circuit. The first rectifying circuit is configured to detect an envelope of an input signal, and provide an envelope detection signal comprising a first direct current (DC) offset voltage. The second rectifying circuit is configured to provide a second DC offset voltage corresponding to the first DC offset voltage. The first arithmetic circuit is configured to provide an envelope signal in which the first DC offset voltage is reduced through subtraction between the envelope detection signal and the second DC offset voltage.

Provided is an electric transmission cable module that has both a squelch function and an AGC function, and realizes a highly accurate function while suppressing an increase in chip cost. Disclosed is an electric transmission cable module including a first amplifier that compensates for a cable loss of a conductive cable, a second amplifier having a variable gain function, a third amplifier allowed to transit between a normal state for amplifying a signal and an idle state having smaller power consumption than power consumption in the normal state, a detector that detects a signal level on a signal transmission line between the first amplifier and the third amplifier, an analog-to-digital conversion circuit that converts the signal level into a digital signal, a first control circuit that generates a gain adjustment signal for controlling a gain of the second amplifier based on the digital signal, and a second control circuit that controls transition between the normal state and the idle state of the third amplifier based on the digital signal.

A curve fitting circuit, an analog predistorter, and a radio frequency signal transmitter are disclosed. Each segmentation processing circuit in the curve fitting circuit generates a to-be-processed signal according to a intercepted part of a received signal, and generates q output signals according to the to-be-processed signal. Parts intercepted by different segmentation processing circuits are not exactly the same. Each first adder circuit in the curve fitting circuit receives one signal in the q output signals of each segmentation processing circuit, and obtains one output signal of the curve fitting circuit according to a sum of received n signals.

A power amplifier module includes an amplifier transistor and a bias circuit. A first power supply voltage based on a first operation mode or a second power supply voltage based on a second operation mode is supplied to the amplifier transistor. The amplifier transistor receives a first signal and outputs a second signal obtained by amplifying the first signal. The bias circuit supplies a bias current to the amplifier transistor. The bias circuit includes first and second resistors and first and second transistors. The first transistor is connected in series with the first resistor and is turned ON by a first bias control voltage which is supplied when the first operation mode is used. The second transistor is connected in series with the second resistor and is turned ON by a second bias control voltage which is supplied when the second operation mode is used.

Methods and systems for modulating an amplifier power supply to efficiently attain amplified RF output power with much lower power dissipation than existing amplifiers. In a cable television (CATV) network, a processor receives a signal to be amplified by an amplifier at a location remote from the processor. A bias point of the amplifier may be variably modulated based on peaks of an input signal to reduce amplifier dissipation.