A circuit arrangement is provided which includes an array of stages for photon counting current to voltage conversion. Each stage includes a tunable operational transconductance amplifier and a feedback network forming a feedback loop of the operational transconductance amplifier. Each stage is configured to provide an output signal as a function of an input signal that is provided to the amplifier input of the operational transconductance amplifier, wherein the input signal comprises one or more current pulses and the output signal comprises one or more voltage pulses. With the tunable operational transconductance amplifier the transconductance of a stage can be tuned so that differences in peaking time and gain are avoided. Furthermore, an imaging device and a method for operating a circuit arrangement are provided.

A shaper circuit includes a first amplifier including an input and an output, the input being configured to receive an input signal, which includes one or more current pulses, a feedback component coupled to the output and to the input of the first amplifier thereby forming a feedback loop of the first amplifier, and an RC component coupled to the output of the first amplifier and to a reference potential terminal. Therein the shaper circuit is configured to provide an output signal as a function of the input signal, the output signal including one or more voltage pulses, and the RC component is configured to largely cancel a low frequency pole of the feedback loop of the first amplifier.

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.

The present disclosure relates to devices and methods for detecting and preventing occurrence of a saturation state in a power amplifier. A power amplifier module can include a power amplifier including a cascode transistor pair. The cascode transistor pair can include a first transistor and a second transistor. The power amplifier module can include a current comparator configured to compare a first base current of the first transistor and a second base current of the second transistor to obtain a comparison value. The power amplifier module can include a saturation controller configured to supply a reference signal to an impedance matching network based on the comparison value. The impedance matching network can be configured to modify a load impedance of a load line in electrical communication with the power amplifier based at least in part on the reference signal.

Bias circuits and methods for silicon-based amplifier architectures that are tolerant of supply and bias voltage variations, bias current variations, and transistor stack height, and compensate for poor output resistance characteristics. Embodiments include power amplifiers and low-noise amplifiers that utilize a cascode reference circuit to bias the final stages of a cascode amplifier under the control of a closed loop bias control circuit. The closed loop bias control circuit ensures that the current in the cascode reference circuit is approximately equal to a selected multiple of a known current value by adjusting the gate bias voltage to the final stage of the cascode amplifier. The final current through the cascode amplifier is a multiple of the current in the cascode reference circuit, based on a device scaling factor representing the relative sizes of the transistor devices in the cascode amplifier and in the cascode reference circuit.

This application relates to circuitry for monitoring for instability of an amplifier. The amplifier (100) has a first signal path between an amplifier input (IN.sub.N) and an amplifier output (V.sub.OUT) and a feedback path from the output to form a feedback loop with at least part of the first signal path. A comparator (212) has a first input configured to receive a first signal (IN.sub.N) derived from a first amplifier node which is part of said feedback loop and a second input configured to receive a second signal (IN.sub.P) derived from a second amplifier node which varies with the signal at the amplifier input but does not form part of said feedback loop. The comparator is configured to compare the first signal to the second signal and generate a comparison signal (COMP), wherein in the event of amplifier instability the comparison signal comprises a characteristic indicative of amplifier instability.

The invention relates to a method for controlling a driver circuit. The method comprises operating an amplifier for providing an output signal, for example an electronic signal for driving or controlling a load, for example a voltage or a current, based on a control signal. The method further comprises operating a comparator for providing the control signal by comparing an input signal, for example an electronic signal with a lower level or a lower amplitude than the output signal, to a feedback signal, wherein the feedback signal is based on the output signal. The method further comprises providing a first supply voltage to the comparator, and providing a second supply voltage to the amplifier, wherein the second supply voltage is higher than the first supply voltage.

An envelope tracking supply modulator for a power amplifier is disclosed. The envelope tracking supply modulator comprises a multilevel push-pull converter. The multilevel push-pull converter comprises a control logic configured to generate a first and second control signals based on an envelope reference signal; a source multilevel converter configured to receive the first control signal and generate a source multilevel power supply signal; a sink multilevel converter configured to receive the second control signal and generate a sink multilevel power supply signal. The envelope tracking supply modulator further comprises a power recycling supply coupled to the sink multilevel converter; a low-pass filter coupled to outputs of the source and sink multilevel converters to filter the power supply signals generated from the source and sink multilevel converters.

An embodiment pulse-width modulation (PWM) modulator circuit comprises a first half-bridge stage having a first output node and a second half-bridge stage having a second output node. The first output node and the second output node are configured to have an electrical load coupled therebetween to apply thereto a PWM-modulated output signal. The circuit comprises a differential stage having input nodes configured to receive an input signal applied between the input nodes and produce a differential control signal for the first half-bridge stage and the second half-bridge stage. A current comparator is arranged intermediate the differential stage and the first and second half-bridge stages. The current comparator is configured to produce a PWM-modulated drive signal to drive the half-bridge stages as a function of the input signal applied between the input nodes in the differential stage.

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.