An envelope tracking supply modulator includes an amplifier circuit and a zero peaking circuit. The amplifier circuit receives an envelope input, generates a modulated supply voltage according to the envelope input, and provides the modulated supply voltage to a power amplifier. The zero peaking circuit is coupled to the amplifier circuit, and applies zero peaking to the amplifier circuit, where the zero peaking inserts a zero at a frequency.

Embodiments of a Doherty power amplifier that maintain efficiency over a large operating average power range are disclosed. In one embodiment, the Doherty power amplifier includes reconfigurable main and auxiliary output matching networks and a fixed combining network. The reconfigurable main and auxiliary output matching networks can be reconfigured such that together the reconfigurable main output matching network, the reconfigurable auxiliary output matching network, and the fixed combining network provide proper load modulation for multiple different back-off power levels. As a result, the Doherty power amplifier maintains high efficiency over an extended back-off power level range.

A high-frequency front-end circuit includes a plurality of power amplifiers. Power supply inductors and matching inductors for the power amplifiers are formed of conductors disposed on a substrate. The power supply inductors and the matching inductors are disposed on or in different layers. When the substrate is seen in a plan view, at least a portion of the first power supply inductor and at least a portion of the second matching inductor overlap each other with an insulating layer interposed therebetween.

Described embodiments provide a radio frequency (RF) amplifier system having at least one amplifier. The at least one amplifier includes an RF input port, an RF output port and a drain bias port. At least one voltage modulator is coupled to the bias port of the least one amplifier to provide a bias voltage. The bias voltage is selected by switching among a plurality of discrete voltages. At least one filter circuit is coupled between the at least one voltage modulator and the at least one amplifier. The at least one filter circuit controls spectral components resultant from transitions in the bias voltage when switching among the plurality of discrete voltages. A controller dynamically adapts at least one setting of the at least one voltage modulator by using multi-pulse transitions when switching among the plurality of discrete voltages for a first operating condition of the RF amplifier.

A power amplifier has improved power added efficiency at high output power. The power amplifier includes: a first transistor for amplifying an input signal input to the base thereof and outputting the amplified signal from the collector thereof; a second transistor with power-supply voltage applied to the collector thereof to supply bias voltage or bias current from the emitter thereof to the base of the first transistor; a third transistor whose collector is connected to the collector of the first transistor to amplify the input signal input to the base thereof and output the amplified signal from a collector thereof; a fourth transistor whose base and collector are connected to supply bias from the emitter thereof to the base of the third transistor; and a first resistor with bias control voltage applied to one end thereof and the other end connected to the bases of the second and fourth transistors.

A communication device includes a power amplifier that generates power signals according to one or more operating bands of communication data, with the amplitude being driven and generated in output stages of the power amplifier. The final stage can include an output passive network that suppresses suppress an amplitude modulation-to-phase modulation (AM-PM) distortion. During a back-off power mode a bias of a capacitive unit of the output power network component can be adjusted to minimize an overall capacitance variation. A output passive network can further generate a flat-phase response between dual resonances of operation.

This invention aims to present a smart and dynamic power amplifier module that features both power combining and power sharing capabilities. The proposed flexible power amplifier (PA) module consists of a pre-processor, N PAs, and a post-processor. The pre-processor is an M-to-N wavefront (WF) multiplexer (muxer), while the post processor is a N-to-M WF de-multiplexer (demuxer), where N≧M≧2. Multiple independent signals can be concurrently amplified by a proposed multi-channel PA module with a fixed total power output, while individual signal channel outputs feature different power intensities with no signal couplings among the individual signals. In addition to basic configurations, some modules can be configured to feature both functions of parallel power amplifiers and also as M-to-M switches. Other programmable features include configurations of power combining and power redistribution functions with a prescribed amplitude and phase distributions, as well as high power PA with a linearizer.

A radio frequency (RF) power transistor circuit includes a power transistor and a decoupling circuit. The power transistor has a control electrode coupled to an input terminal for receiving an RF input signal, a first current electrode for providing an RF output signal at an output terminal, and a second current electrode coupled to a voltage reference. The decoupling circuit includes a first inductive element, a first resistor, and a first capacitor coupled together in series between the first current electrode of the power transistor and the voltage reference. The decoupling circuit is for dampening a resonance at a frequency lower than an RF frequency.

Various methods and circuital arrangements for protection of a power amplifier from over voltage are presented. According to one aspect, a protection circuit coupled to a varying supply voltage of the power amplifier controls a biasing current to the power amplifier to limit a power dissipation through the power amplifier. An overvoltage protection circuit detects a level of the varying supply voltage and decreases the biasing current as a linear function of an increasing supply voltage once the supply voltage reaches a programmable voltage level. A slope of the linear function can be made programmable. Programmability of the voltage level and the slope can be used to control biasing currents to a plurality of power amplifiers operating at different times and having different requirements in terms of voltage limits and thermal breakdown. According to another aspect a voltage to current converter for use in the overvoltage protection circuit is presented.

A Doherty amplifier is configured in such a manner that: the ratio Z.sub.3/Z.sub.2 of a characteristic impedance Z.sub.3 of a second transmission line to a characteristic impedance Z.sub.2 of a first transmission line is a power division ratio P.sub.2/P.sub.3 of a signal to be amplified between a carrier amplifier and a peak amplifier when both of the carrier amplifier and the peak amplifier are saturated; and a resistance value R.sub.iso of a resistor is a value obtained by multiplying, by a proportionality coefficient w which is equal to or greater than 0 but less than 1, the sum of the input impedance Z.sub.cin0 of the carrier amplifier when the carrier amplifier reaches saturation and the input impedance Z.sub.pin0 of the peak amplifier when the peak amplifier reaches saturation.