An integrated circuit having a plurality of miniaturized transistors, wherein the plurality of transistors include: high concentration transistors which include channel regions having impurity concentrations of a first concentration; and low concentration transistors which include channel regions having impurity concentrations of a second concentration lower than the first concentration.

A bias circuit includes a replica circuit for an amplifier circuit using a cascode type inverter, and a generation circuit that generates a bias voltage that causes a drain voltage of an input stage transistor of the amplifier circuit to be a saturation drain voltage, based on an output voltage of the replica circuit, and supplies the generated bias voltage to a cascode element of the amplifier circuit and a cascode element of the replica circuit.

The present disclosure provides a trans-impedance amplifier, comprising: an equivalent secondary amplifier module, having an input end and an output end, wherein the input end is coupled to an optical diode and used for accessing an input voltage signal, and the output end is used for outputting a secondarily amplified first voltage signal; an inverting amplifier unit, coupled to the output end of the equivalent secondary amplifier module and used for accessing the first voltage signal and outputting an inverting amplified voltage signal, the inverting amplifier unit comprising a third N-type transistor and a fourth N-type transistor coupled to the third N-type transistor; and a feedback resistor, coupled to the input end of the equivalent secondary amplifier module and an output end of the inverting amplifier unit. The feedback resistor of the trans-impedance amplifier can be not restricted by original conditions, may increase resistance, reduce input noise and improve sensitivity.

A system includes a class D amplifier and a current steering digital-to-analog converter (DAC) directly connected to the class D amplifier. The system also includes a common mode servo circuit coupled to a node interconnecting the current steering DAC to the class D amplifier. The common servo circuit amplifies a difference between a common mode signal determined from the node and a reference voltage and generates a feedback current to the node based on the amplified difference. A feed-forward common-mode compensation circuit is included to reduce an alternating current (AC) ripple from the class D amplifier. The feed-forward common-mode compensation circuit includes first and second resistors coupled to respective outputs of the class D amplifier. A current mirror is coupled to the first and second resistors and is configured to sink a current from the node to ground that approximates a common mode feedback current of the class D amplifier.

An embodiment discloses an operational amplifier comprising: an input stage; an output stage communicatively coupled to the input stage, wherein the output stage further comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a first current source, a fifth transistor, a sixth transistor and a second current source, wherein a second node of the first transistor is connected to the input stage (vin), a third node of the first transistor is connected to a third node of the fourth transistor, ground (gnd), a third node of the fifth transistor and a third node of the third transistor, a first node of the first transistor is connected to a first node of the first current source, a second node of the sixth transistor and a second node of the second transistor.

A power amplifier circuit includes a differential to single-ended converter, a gain stage circuit, a driver stage circuit, and an output stage circuit connected in series, and a bias circuit connected to a bias voltage port of the gain stage circuit for adjusting a bias voltage of the gain stage circuit. The bias voltage is adjustable to ensure low power consumption, improve the efficiency of the power amplifier circuit and prevent process, voltage and temperatures from affecting the performance of the power amplifier circuit.

The amplifier circuit includes a pair of differential input stages coupled to an output stage where both a selected input stage and an unselected input stage are active with one of either a differential input signal or a reference voltage. A switching network couples a first input differential signal to a first differential input stage and a reference voltage to a second differential input stage when an amplifier input signal is less than a threshold voltage. The switching circuit also couples the second input differential signal to the second differential input stage and the reference voltage to the first differential input stage when the amplifier input signal is greater than the threshold signal.

An output signal can be free of any noise component generated from an amplifier disposed in a path, without degradation of the S/N ratio of the output signal. An amplifier includes: a first amplifier that is connected to an input node and generates a first intermediate signal; a feedback resistor that enables feedback of the first intermediate signal to the input node; an attenuator that receives the first intermediate signal and generates a second intermediate signal; a second amplifier that is connected to the input node and generates a third intermediate signal; a third amplifier that is connected to the input node and generates a fourth intermediate signal; and an adder that generates an output signal, using the second intermediate signal, the third intermediate signal, and the fourth intermediate signal.

A driver circuit including a first op-amp, a second op-amp, and a power switching circuit is provided. The first op-amp includes a first input stage circuit for generating a first amplified signal and a first output stage circuit. The second op-amp includes a second input stage circuit for generating a second amplified signal and a second output stage circuit. The power switching circuit includes a first output terminal for outputting one of the first amplified signal and the second amplified signal and a second output terminal for outputting the other of the first amplified signal and the second amplified signal. The power switching circuit is configured to switch a first power supply for both the first input stage circuit and the second input stage circuit between a first supply voltage and a second supply voltage in response to the control signal.

An amplifier includes a first stage and a second stage. The first stage includes a first output and a second output. The second stage includes an output, a first transistor and a second transistor. The first transistor includes a drain coupled to the first output of the first stage, and a source coupled to the output of the second stage. The second transistor includes a drain coupled to the second output of the first stage, and a gate coupled to the output of the second stage.