A comparator includes a folded cascode stage having positive and negative outputs. The folded cascode stage includes: a common-mode voltage regulation circuit that includes resistive elements that are respectively situated between each of the outputs and a common-mode node. A compensation circuit is configured to regulate a difference between the voltages on the outputs, and is configured to generate a constant and continuous compensation current in the two resistive elements. A hysteresis circuit is configured to offset voltages on the outputs, and to generate a hysteresis current in the two resistive elements.

An operational amplifier is disclosed. The operational amplifier activates/couples either a first or a second differential pair of transistors to an input based on the input voltage. The first and second pair of transistors are each biased with a current having a first portion that is constant with temperature and a second portion that is proportional to temperature. By adjusting the ratios of the first and second portions, the transconductance of each differential pair may be made relatively constant with temperature. Each differential pair is coupled to a trim current source that is adjusted to reduce the voltage offset at each output. The resulting voltage offset for the operational amplifier is relatively constant over a range of input voltages and has temperature coefficient unaffected by the trimming process.

A voltage regulator includes a first switch connected between a first input terminal of an error amplifier circuit and an input terminal of the voltage regulator, a second switch connected between a second input terminal of the error amplifier circuit and an output terminal of the voltage regulator, a third switch connected between the first input terminal and the second input terminal, and a short fault detection circuit which detects a short fault of the output terminal, based on an output voltage of the voltage regulator.

A chopper amplifier circuit includes a first amplifier path with chopper circuitry, a switched-capacitor filter, and multiple gain stages. The chopper amplifier circuit also includes a second amplifier path with a feed-forward gain stage. A chopping frequency of the chopper circuitry is greater than a threshold frequency at which the second amplifier path is used instead of the first amplifier path.

A source driver includes an interpolation amplifier configured to generate an interpolation voltage based on a received plurality of input voltages and output the interpolation voltage to a display panel; and an input selector configured to receive a first voltage and a second voltage having a different level from the first voltage, and configured to selectively provide at least one of the first and second voltages as the plurality of input voltages in response to some of the lower bits of pixel data. The interpolation amplifier includes four conductive differential input pairs configured to receive four input voltages from among the plurality of input voltages, respectively. Each of the first differential input pair and third differential input pair comprises a first type transistor. Each of the second differential input pair and fourth differential input pair comprises a second type transistor.

A supply modulator for a polar power amplifier and method for operating the same are disclosed. An apparatus includes an amplifier having an input for receiving a phase modulated (PM) signal. A modulator is arranged to receive an amplitude modulated (AM) signal and provide a supply voltage to the amplifier, the supply voltage varying based on the AM signal. A detector circuit may detect the supply voltage exceeding a first threshold or falling below a second threshold. The detector circuit includes a current source arranged to provide a bias current to the modulator. When the supply voltage exceeds the first threshold, the detector causes an increase in the bias current provided to the modulator. Similarly, when the supply voltage falls below a second threshold, the detector causes an increase of the bias current supplied to the modulator.

The present invention provides a class AB amplifier, wherein the class AB amplifier includes a cascode stage with a filter and an output stage. The cascode stage with the filter is arranged for receiving an input signal to generate a first driving signal and a second driving signal, wherein the filter filters the input signal to generate an filtered input signal, and at least one of the first driving signal and the second driving signal is generated according to the filtered input signal. The output stage is coupled to the cascode stage, and is arranged for generating an output signal according to the first driving signal and the second driving signal.

Provided is a transconductance amplifier including a common-mode feedback circuit that does not affect an operation of the transconductance amplifier. The transconductance amplifier has a transconductance amplifier circuit configured to generate an output current based on an input voltage and a common-mode feedback circuit configured to determine a DC operating point of an output of the transconductance amplifier circuit. The common-mode feedback circuit has a plurality of level shift circuits configured to shift levels of input voltages to output the voltages, and are connected to control terminals of a plurality of transistors.

A class AB amplifier with improved DC gain. An amplifier includes an input stage and an output stage. The output stage is configured to amplify an output of the input stage. The output stage includes output transistors, class AB amplifier circuitry, minimum selector circuitry, and gain boost amplifier circuitry. The class AB amplifier circuitry includes a first transistor and a second transistor connected as a differential amplifier. The minimum selector circuitry is configured to control bias current in the output transistors by driving a control input of the first transistor. The gain boost amplifier circuitry is coupled to the class AB amplifier circuitry. The gain boost amplifier circuitry is configured to drive a common mode signal onto the control input of the first transistor and a control input of the second transistor, the common mode signal based on the output of the input stage.

Methods, circuits, and apparatuses that provide Buffer Amplifier, containing Amplifiers and Buffer Drivers, one or more of the following: ultra low power Buffer Amplifier, capable of having high gain, low noise, high speed, near rail-to-rail input-output voltage span, high sink-source current drive capability for an external load, and able to operate at low power supply voltages. Methods, circuits, and apparatuses that provide regulated cascode (RGC) current mirrors (CM) capable of operating at low power supply and having wide input-output voltage spans.