An operational amplifier includes a single-stage amplifier and a current controller. The single-stage amplifier receives an input signal, and amplifies the input signal to generate an output signal, wherein the single-stage amplifier includes a voltage controlled current source circuit that operates in response to a bias voltage input. The current controller receives the input signal, and generates the bias voltage input according to the input signal. The bias voltage input includes a first bias voltage, a second bias voltage, a third bias voltage, and a fourth bias voltage. None of the first bias voltage, the second bias voltage, the third bias voltage, and the fourth bias voltage is directly set by the input signal of the single-stage amplifier.

A differential amplifier comprises: a long tailed pair transistor configuration comprising a differential pair of transistors and a tail transistor; and a replica circuit configured to vary a feedback current in the replica circuit to match a replica voltage to a reference voltage, wherein varying the feedback current in the replica circuit 4 provides a bias voltage to the tail transistor in the long tailed pair which controls a tail current through the tail transistor to determine a common mode voltage in the long tailed pair.

Described herein is a fully-differential preamplifier comprising an input differential pair, an output current load, and a current source. The current source is coupled between the input differential pair and a low voltage rail and configured to control whether the fully-differential preamplifier is operating in a first mode or a second mode, wherein the preamplifier draws more current when operating in the second mode compared to when operating in the first mode. The input differential pair is coupled between the output current load and the current source. The output current load is coupled between a high voltage rail and the input differential pair. The input differential pair comprise positive and negative inputs of the fully-differential preamplifier. Nodes where the input differential pair and the output current load are coupled to one another comprise positive and negative outputs of the fully-differential preamplifier.

A fully differential amplifier includes: an input stage comprising a first amplification circuit and a second amplification circuit, one of which is configured to generate a push signal and the other of which is configured to generate a pull signal, each by amplifying a differential input signal; an output stage for generating a differential output signal based on the push signal and the pull signal; and a feedback circuit for providing common mode feedback to the first amplification circuit based on the differential output signal, wherein the second amplification circuit may include a passive network for setting a common mode voltage of the push signal or the pull signal.

An operational amplifier includes a single-stage amplifier and a current controller. The single-stage amplifier receives an input signal, and amplifies the input signal to generate an output signal, wherein the single-stage amplifier includes a voltage controlled current source circuit that operates in response to a bias voltage input. The current controller receives the input signal, and generates the bias voltage input according to the input signal.

A method for performing common mode voltage re-biasing in an analog front-end circuit of a receiver, an associated common mode voltage re-biasing circuit, the receiver and an associated integrated circuit are provided. The common mode voltage re-biasing circuit may include a control circuit and multiple switchable common mode voltage re-biasing sub-circuits. The control circuit generates at least one control signal according to a command, for controlling the common mode voltage re-biasing circuit to operate in a selected circuit configuration. The multiple switchable common mode voltage re-biasing sub-circuits select a predetermined circuit configuration from a first predetermined circuit configuration and a second predetermined circuit configuration according to the at least one control signal to be the selected circuit configuration to perform common mode voltage re-biasing operations corresponding to the selected circuit configuration, respectively.

Described herein is a fully-differential preamplifier comprising an input differential pair, an output current load, and a current source. The current source is coupled between the input differential pair and a low voltage rail and configured to control whether the fully-differential preamplifier is operating in a first mode or a second mode, wherein the preamplifier draws more current when operating in the second mode compared to when operating in the first mode. The input differential pair is coupled between the output current load and the current source. The output current load is coupled between a high voltage rail and the input differential pair. The input differential pair comprise positive and negative inputs of the fully-differential preamplifier. Nodes where the input differential pair and the output current load are coupled to one another comprise positive and negative outputs of the fully-differential preamplifier.

An operational amplifier includes a single-stage amplifier and a current controller. The single-stage amplifier receives an input signal, and amplifies the input signal to generate an output signal, wherein the single-stage amplifier includes a voltage controlled current source circuit that operates in response to a bias voltage input. The current controller receives the input signal, and generates the bias voltage input according to the input signal. The bias voltage input includes a first bias voltage, a second bias voltage, a third bias voltage, and a fourth bias voltage. None of the first bias voltage, the second bias voltage, the third bias voltage, and the fourth bias voltage is directly set by the input signal of the single-stage amplifier.

A fully differential amplifier includes: an input stage comprising a first amplification circuit and a second amplification circuit, one of which is configured to generate a push signal and the other of which is configured to generate a pull signal, each by amplifying a differential input signal; an output stage for generating a differential output signal based on the push signal and the pull signal; and a feedback circuit for providing common mode feedback to the first amplification circuit based on the differential output signal, wherein the second amplification circuit may include a passive network for setting a common mode voltage of the push signal or the pull signal.

An operational amplifier includes a single-stage amplifier and a current controller. The single-stage amplifier receives an input signal, and amplifies the input signal to generate an output signal, wherein the single-stage amplifier includes a voltage controlled current source circuit that operates in response to a bias voltage input. The current controller receives the input signal, and generates the bias voltage input according to the input signal.