A power amplifier circuit includes a first amplifier that operates in accordance with a first voltage supplied from a voltage supply source, amplifies a first signal, and outputs an amplification signal, a bias transistor that includes a base or a gate to which a bias control current is supplied and an emitter or a source supplying a bias to the first amplifier through a first resistor element, and a protection circuit that causes part of the bias control current to flow to a ground on the basis of the amplification signal and a second signal based on the first voltage.

This invention relates to current sensing, in particular for a signal processing circuit (500) for outputting an output signal (Sout) based on an input signal (Sin). An output stage (101) includes an output transistor (102) driven, in use, by a drive signal. A current monitor (501) is configured to monitor, in use, a first current through the output transistor, wherein the current monitor comprises a current sensor (105) having a sense transistor (106) configured to be driven based on the drive signal so as to generate a sense current related to the first current. A compensation controller (301) receives an indication of signal level of the input signal and controllably varies operation of the current monitor (501) so as to at least partially compensate for signal-dependent variation in a relationship between the first current and the first sense current.

This application relates to methods and apparatus for power limiting for amplifiers. An amplifier is configured to receive an input supply voltage and to draw, in use, an amplifier input current resulting in an amplifier input power. A power limiter is configured to monitor an indication of the amplifier input power, determine a first signal limit based on said indication of the amplifier input power and a pre-set limit and apply regulation to the input signal to provide a regulated input signal for input to the amplifier that does not exceed the first signal limit.

Power protection loops for amplifier chain elements are disclosed. In one aspect, an amplifier chain may have a power detection circuit detect power within the amplifier chain. When the power exceeds a threshold, a control circuit limits amplification provided by amplifier element(s) within the amplifier chain to throttle or lower power levels within the amplifier chain, thereby protecting elements within the amplifier chain. In this fashion, not only may the amplifier element(s) be protected, but also acoustic filter elements may be protected. The threshold used to throttle or lower the power levels may be based on one or more of: a supply voltage, a sensed temperature, and a mode (e.g., 2G, 3G, 4G, 5G). By protecting these elements, these elements survive power surges instead of failing.

An amplification circuit includes a switch circuit, an amplifier, and a control circuit. The switch circuit has a first terminal coupled to a radio frequency signal input terminal or a system voltage terminal, a second terminal coupled to an input terminal of the amplifier, and a control terminal configured to receive a control signal. The amplifier amplifies a radio frequency signal. The control circuit generates the control signal according to a driving current generated by the amplifier. When the control circuit determines that the amplifier operates in a high power mode, the control circuit controls the control signal to adjust a conducting level between the first terminal and the second terminal of the switch circuit according to the intensity of the driving current.

This application relates to current sensing, in particular for a signal processing circuit (500) for outputting an output signal (Sout) based on an input signal (Sin). An output stage (101) includes an output transistor (102) driven, in use, by a drive signal. A current monitor (501) is configured to monitor, in use, a first current through the output transistor, wherein the current monitor comprises a current sensor (105) having a sense transistor (106) configured to be driven based on the drive signal so as to generate a sense current related to the first current. A compensation controller (301) receives an indication of signal level of the input signal and controllably varies operation of the current monitor (501) so as to at least partially compensate for signal-dependent variation in a relationship between the first current and the first sense current.

Components of a power amplifier controller may support lower voltages than the power amplifier itself. As a result, a surge protection circuit that prevents a power amplifier from being damaged due to a power surge may not effectively protect the power amplifier controller. Embodiments disclosed herein present an overvoltage protection circuit that prevents a charge-pump from providing a voltage to a power amplifier controller during a detected surge event. By separately detecting and preventing a voltage from being provided to the power amplifier controller during a surge event, the power amplifier controller can be protected regardless of whether the surge event results in a voltage that may damage the power amplifier. Further, embodiments of the overvoltage protection circuit can prevent a surge voltage from being provided to a power amplifier operating in 2G mode.

A transmitting and receiving device having a module (GSZ) with a configurable HF high-power amplifier (HPA) that includes a main power amplifier (DM) with a main amplifier core and at least one peak power amplifier (DP1) having an auxiliary amplifier core. A switching element connected to inputs of the main power amplifier and the at least one peak power amplifier is connected to a digital input signal divider (ET) having a plurality of outputs and an output combiner (C) is connected to outputs of the amplifier cores for the main power amplifier and the at least one peak power amplifier. A multi-harmonic transformation line (LAH) is connected at the amplifier core output of the main power amplifier and at the amplifier core output of the at least one peak power amplifier, and a circulator (Z1) is connected to the output of the output combiner or an impedance converter (AN1).

An amplifier overload power limit circuit, system, and a method thereof comprising a monitoring of a current gain of a BJT based on a current detector and limiting power to the BJT based on the monitored current gain to prevent the BJT from driven into a saturation mode and the amplifier overdrive.

A digitally modulated polar power amplifier uses a thin-oxide amplifying transistor with a protection diode. The polar power includes a driver amplifier in a driver stage that can receive a phase-modulated signal with a constant envelope and amplify the signal for the output stage, which includes only a single thin-oxide transistor, leading to improved efficiency over systems that require a thick-oxide transistor. A protection diode can be added between the output of the polar power amplifier and the supply voltage to limit the output to the sum of the supply voltage plus the forward voltage of the diode. Amplitude modulation can be achieved through dynamically turning on and off the digital power amplifier via an amplitude control word (acw) input signal.