A bias generation method or apparatus defined by any one or any practical combination of numerous features that contribute to low noise and/or high efficiency biasing, including: having a charge pump control clock output with a waveform having limited harmonic content or distortion compared to a sine wave; having a ring oscillator to generating a charge pump clock that includes inverters current limited by cascode devices and achieves substantially rail-to-rail output amplitude; having a differential ring oscillator with optional startup and/or phase locking features to produce two phase outputs suitably matched and in adequate phase opposition; having a ring oscillator of less than five stages generating a charge pump clock; capacitively coupling the clock output(s) to some or all of the charge transfer capacitor switches; biasing an FET, which is capacitively coupled to a drive signal, to a bias voltage via an “active bias resistor” circuit that conducts between output terminals only during portions of a waveform appearing between the terminals, and/or wherein the bias voltage is generated by switching a small capacitance at cycles of said waveform. A threshold voltage bias voltage generation circuit may A charge pump for the bias generation may include a regulating feedback loop including an OTA that is also suitable for other uses, the OTA having a ratio-control input that controls a current mirror ratio in a differential amplifier over a continuous range, and optionally has differential outputs including an inverting output produced by a second differential amplifier that optionally includes a variable ratio current mirror controlled by the same ratio-control input. The ratio-control input may therefore control a common mode voltage of the differential outputs of the OTA. A control loop around the OTA may be configured to control the ratio of one or more variable ratio current mirrors, which may particularly control the output common mode voltage, and may control it such that the inverting output level tracks the non-inverting output level to cause the amplifier to function as a high-gain integrator.

The audio amplification system comprises a power supply (100) connected to a feedback circuit (107), which is connected to the amplifier output filter, so that the power supply voltage (100) dynamically adjusts to the amplifier output voltage. Connected to the power supply (100) and mosfets (102) is a capacitor (108) with the function of stabilizing the power supply voltage (100). The system also comprises a control circuit (106), in which the mosfets (102) are connected, which connect to the output filter through an inductor (103) and a capacitor (104). The amplifier output (101) involves a speaker (105).

An envelope detection circuit and methods for detecting an envelope of a signal using such an envelope detection circuit. One example envelope detection circuit generally includes a first diode, a capacitive element, and a clamping circuit. The first diode has an anode coupled to an input node of the envelope detection circuit and has a cathode coupled to an output node of the envelope detection circuit. The capacitive element is coupled in shunt between the output node and a reference potential node, and the clamping circuit is coupled in shunt between the input node and the reference potential node. The clamping circuit generally includes a resistive element coupled in series with a second diode.

A low frequency loss correction circuit that improves the efficiency of a power amplifier at near-DC low frequencies The low frequency loss correction circuit can include a signal error detection circuit configured to produce an error signal in response to detecting one or more frequency components of a tracking signal below a cutoff frequency that are substantially attenuated through a capacitive path. The low frequency loss correction circuit can include a drive circuit configured to convert the error signal into a low frequency correction signal, and provide the low frequency correction signal to a voltage supply line, the low frequency correction signal including at least some of the one or more frequency components of the tracking signal below a cutoff frequency that are substantially attenuated through the capacitive path.

A wave shaping circuit reduces slope magnitudes during increasing and decreasing voltage transitions. The wave shaping circuit includes a first switch that receives an input voltage having at least two voltage values where an input voltage transition between the at least two voltage values has a first slope magnitude; an inductor connected in series with the first switch; a second switch connected in a parallel arrangement with the first switch and the inductor; and a capacitor having a first end connected between the inductor and an output port and a second end connected to ground. When the input voltage begins the input voltage transition to a higher voltage value, the first switch turns on and the second switch turns off, such that the inductor limits current flow from the input voltage, decreasing a second slope magnitude of an output voltage transition to less than the first slope magnitude.

The invention relates to a broadband high power amplifier that comprises a signal input adapted to receive an input signal, at least one amplifier stage adapted to amplify the received input signal, a signal output adapted to output the signal amplified by the at least one amplifier stage as an output signal, a monitoring unit adapted to monitor signal characteristics of the input signal and the output signal and a control unit adapted to operate the at least one amplifier stage at an optimal operating point depending on the current signal characteristics monitored by said monitoring unit.

A solid state power amplifier uses a Doherty power amplifier that can be implemented as a monolithic microwave integrated circuit. By adjusting the DC bias of the amplifying stages in each branch of the Doherty amplifier, the output power, linearity, and DC power can be adjusted to provide a specified output, where the specification for the output can include the maintaining of desired DC power and linearity. The Doherty power amplifier can be used in a satellite payload or other application utilizing solid state power amplifiers, while providing the proper amount of RF output power and DC power. A single amplifier can have its bias levels adjusted for different output levels, helping to minimize the number of designs that are required for a given satellite payload, reducing the variety of parts in a satellite payload.

A solid state power amplifier uses a Doherty power amplifier that can be implemented as a monolithic microwave integrated circuit. By adjusting the DC bias of the amplifying stages in each branch of the Doherty amplifier, the output power, linearity, and DC power can be adjusted to provide a specified output, where the specification for the output can include the maintaining of desired DC power and linearity. The Doherty power amplifier can be used in a satellite payload or other application utilizing solid state power amplifiers, while providing the proper amount of RF output power and DC power. A single amplifier can have its bias levels adjusted for different output levels, helping to minimize the number of designs that are required for a given satellite payload, reducing the variety of parts in a satellite payload.

A system may include an analog loop filter comprising a plurality of analog integrators, the analog loop filter configured to receive an analog signal input and a feedback output signal, at least one sampler for sampling outputs of the analog integrators, a second loop filter coupled between an output of an analog pulse-width modulation driver and a digital pulse-width modulation controller, wherein the second loop filter comprises at least one integrator and is configured to receive sampled outputs of the analog integrators from the at least one sampler and receive a feedback pulse-width modulation signal from the analog pulse-width modulation driver, and a correction subsystem configured to apply a non-linear function to a signal path of the second loop filter in order to compensate for non-linearity introduced as a result of sampling outputs of the analog integrators.

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.