A variable gain amplifier utilizing positive feedback and time-domain calibration includes an integration phase and a regeneration phase. A current source provides a bias current that increases linearity in the integration phase and reduces common-mode voltage dependence. The circuit includes a timing control loop, wherein a variable gain of a residue amplifier is proportional to a first time that a timing control loop signal is kept high, as determined by an on or off status of respectively paired inverter assemblies each having an input voltage determined by an amplifier output voltage during the regeneration phase. A strong-arm latch structure acts as a positive feedback latch until the first time is de-asserted.

A sampling circuit includes: an amplifier, having a characteristic that settling time in a case where an output voltage of the sampling circuit is lowered and the settling time in a case where the output voltage is raised are different; a capacitor, charged by an input voltage from the amplifier; a first switch, switching a connection state between an output of the amplifier and the capacitor; a second switch, connected in parallel with the capacitor, and switching a connection state between the capacitor and a reference potential part whose potential is set according to the characteristic of the amplifier; and a control circuit, controlling switching of each switch. The control circuit performs a first control that switches the first switch off and the second switch on and then performs a second control that switches the first switch on and the second switch off.

This disclosure provides a charging-steering amplifier circuit and the control method thereof. The charging-steering amplifier circuit includes a charging-steering differential amplifier and a sample and hold circuit. The charging-steering amplifier circuit operates in a reset phase or in an amplifying phase to amplify a differential input signal. The control method includes steps of: in the reset phase, obtaining a common mode voltage of the differential input signal according to the differential input signal; in the reset phase, providing the common mode voltage to one of the charging-steering differential amplifier and the sample and hold circuit; in the reset phase, sampling the differential input signal by the sample and hold circuit to generate a voltage signal; and in the amplifying phase, inputting the voltage signal to the charging-steering differential amplifier.

A current sense circuit for a pass transistor is described. The current sense circuit comprises a sense transistor, a differential amplifier comprising a differential input and a differential output, and a differential difference amplifier, referred to as DD amplifier, comprising a main differential input, an auxiliary differential input and an output; wherein the differential output of the differential amplifier is coupled to the auxiliary differential input of the DD amplifier; wherein the output port of the pass transistor is coupled to a first port of the main differential input and wherein the output port of the sense transistor is coupled to a second port of the main differential input. The output of the DD amplifier is used to control a voltage drop across the sense transistor and the pass transistor.

This disclosure provides a charging-steering amplifier circuit and the control method thereof. The charging-steering amplifier circuit includes a charging-steering differential amplifier and a sample and hold circuit. The charging-steering amplifier circuit operates in a reset phase or in an amplifying phase to amplify a differential input signal. The control method includes steps of: in the reset phase, obtaining a common mode voltage of the differential input signal according to the differential input signal; in the reset phase, providing the common mode voltage to one of the charging-steering differential amplifier and the sample and hold circuit; in the reset phase, sampling the differential input signal by the sample and hold circuit to generate a voltage signal; and in the amplifying phase, inputting the voltage signal to the charging-steering differential amplifier.

A dynamic amplifier with a bypass design. An input pair of transistors receives a pair of differential inputs Vip and Vin and further provides first, second and third terminals. A load circuit provides a pair of differential outputs Vop and Von with the load circuit connected at a common mode terminal. In an amplification phase, a driver for amplification is coupled to the first terminal and the load circuit is coupled to the second and third terminals. A bypassing circuit is specifically provided. The bypassing circuit is coupled to the second and third terminals during a bypass period within the amplification phase.

Telescopic amplifier circuits are disclosed. In an embodiment, a telescopic amplifier includes an input stage for receiving differential input signals, an output stage for outputting differential output signals at the drains of a first output transistor and a second output transistor, a tail current transistor coupled to sources of a first input transistor and a second input transistor, a common mode feedback circuit coupled to the differential output signals and outputting a common mode output signal, and a circuit element coupled between the common mode output signal and a gate of the tail current transistor. In an embodiment the circuit element is a resistor. In another embodiment the circuit element is a source follower transistor. In additional embodiments a phase margin of the common mode feedback open loop gain of the amplifier is determined by the value of the resistor. Additional embodiments are disclosed.

The present disclosure relates to a class-D audio amplifier. When the class-D audio amplifier is powered on, an auxiliary power amplifier and an auxiliary feedback circuit constitute an auxiliary close loop so that a control loop is established in advance. The auxiliary close loop is disconnected after various circuit modules reach their steady operation points, and the class-D audio amplifier operates at a normal state. A soft start circuit is provided for suppressing noise which occurs when the class-D audio amplifier is powered on. Thus, the class-D audio amplifier suppresses POP noise at an output terminal when the class-D audio amplifier is powered on.

Systems and methods disclosed herein provide for enhancing the low frequency (DC) gain of an operational amplifier with multiple correlated level shifting capacitors. In an embodiment, the operational amplifier is level shifted with a first correlated level shifting capacitor in a first phase and, then, is level shifted again with at least a second correlated level shifting capacitor in at least a second, non-overlapping, consecutive phase. In an embodiment, the multiple correlated level capacitors are controlled by a switching circuit network.

Telescopic amplifier circuits are disclosed. In an embodiment, a telescopic amplifier includes an input stage for receiving differential input signals, an output stage for outputting differential output signals at the drains of a first output transistor and a second output transistor, a tail current transistor coupled to sources of a first input transistor and a second input transistor, a common mode feedback circuit coupled to the differential output signals and outputting a common mode output signal, and a circuit element coupled between the common mode output signal and a gate of the tail current transistor. In an embodiment the circuit element is a resistor. In another embodiment the circuit element is a source follower transistor. In additional embodiments a phase margin of the common mode feedback open loop gain of the amplifier is determined by the value of the resistor. Additional embodiments are disclosed.