A transimpedance amplifier (TIA) for converting an input current at an input node into an output voltage at an output node, the TIA comprising: a first amplifier stage having a first input coupled to the input node and a first output; a feedback path between the first output and the first input; a second amplifier stage in the feedback path having a second input, the second input coupled to the first output of the first amplifier stage; a feedback resistor in the feedback path coupled between an output of the second amplifier stage and first input of the first amplifier stage; and an output stage, comprising: a load resistor coupled between a reference voltage node and a T-coil, the T-coil comprising first and second inductors coupled in series at an inductor node, the T-coil coupled between the first output and the load resistor, the inductor node coupled to the output node of the TIA.

An amplifier circuit includes an amplifier and an output transistor. The amplifier is coupled to an output node of the output transistor for providing an output voltage to a load device. The amplifier circuit also includes a slew-rate control circuit coupled to a gate node of the output transistor and configured to control voltage rise of the gate node of the output transistor during power-up to reduce output voltage overshoot.

A voltage supply circuit includes a rectifier circuit, a charging circuit, a feedback circuit and an energy storage circuit. The rectifier circuit is used to receive an input voltage to generate a rectified energy. The charging circuit is coupled to the rectifier circuit and has a modulation input terminal and an energy supply terminal. The modulation input terminal is used to receive a modulation voltage, and the energy supply terminal is used to selectively output a charging current according to the modulation voltage. The feedback circuit is used to receive a high voltage signal and a supply voltage, and output the modulation voltage to the modulation input terminal. The feedback circuit is used to adjust the modulation voltage according to a difference between the supply voltage and a reference voltage. The energy storage circuit is charged by the charging current to pull up the supply voltage.

An embodiment amplifier circuit includes a pair of subcircuits that includes a first subcircuit and a second subcircuit, each of which includes a buffer amplifier and a feedback circuit that includes a feedback capacitor. The amplifier circuit also includes a pair of output terminals. The first subcircuit and the second subcircuit each generate a different output signal of a pair of output signals that includes a first output signal and a second output signal. The amplifier circuit is configured for receiving a positive differential input signal at the first subcircuit, receiving a negative differential input signal at the second subcircuit, and receiving the pair of output signals at the pair of output terminals. The amplifier circuit is also configured for transmitting the first output signal to the feedback circuit of the first subcircuit, and transmitting the second output signal to the feedback circuit of the second subcircuit.

A low dropout regulator includes an output circuit and an amplifier. The output circuit includes a signal input end configured to receive an input voltage and a signal output end configured to output an output voltage. The amplifier includes a first stage amplifier circuit, a second stage amplifier circuit, a first feedback circuit and a second feedback circuit. The first stage amplifier circuit includes a positive output end and a negative output end. The second stage amplifier circuit includes an input end and an output end, wherein the input end and the positive output end are coupled at a first node, and the output end is coupled to the output circuit. The first feedback circuit is coupled between the negative output end and the output end. The second feedback circuit is coupled between the first node and the output end.

A voltage supply circuit includes a rectifier circuit, a charging circuit, a feedback circuit and an energy storage circuit. The rectifier circuit is used to receive an input voltage to generate a rectified energy. The charging circuit is coupled to the rectifier circuit and has a modulation input terminal and an energy supply terminal. The modulation input terminal is used to receive a modulation voltage, and the energy supply terminal is used to selectively output a charging current according to the modulation voltage. The feedback circuit is used to receive a high voltage signal and a supply voltage, and output the modulation voltage to the modulation input terminal. The feedback circuit is used to adjust the modulation voltage according to a difference between the supply voltage and a reference voltage. The energy storage circuit is charged by the charging current to pull up the supply voltage.

In accordance with an embodiment, a circuit includes: a first super source follower; a compensation circuit having a compensating node configured to provide a voltage of opposite phase of a voltage of an internal node of the first super source follower; and a first compensation capacitor coupled between an input of the first super source follower and the compensating node of the compensation circuit.

An amplifier circuit includes an amplifier and an output transistor. The amplifier is coupled to an output node of the output transistor for providing an output voltage to a load device. The amplifier circuit also includes a slew-rate control circuit coupled to a gate node of the output transistor and configured to control voltage rise of the gate node of the output transistor during power-up to reduce output voltage overshoot.

An apparatus includes an amplifier. The amplifier has two inputs, and an output. The amplifier has a pole in its transfer function. The frequency of the pole depends on the output current of the amplifier. The amplifier further includes a pole frequency tracking (PFT) circuit. The PFT circuit includes a source follower circuit.

A multi-stage device includes multiple stages such as a first stage and a second stage. During operation, the first stage receives an input signal and outputs an intermediate signal based on the input signal. The second stage is coupled to the first stage to receive the intermediate signal and produce an output signal. According to one configuration, the second stage includes: i) a transistor, and ii) a circuit path between the first stage and the transistor. The transistor component is controlled to derive the output signal from the intermediate signal inputted to the circuit path.