An amplifying circuit includes a reference voltage generating circuit, a common-mode voltage conversion circuit, a common-mode negative feedback circuit, and an amplifying sub-circuit. The reference voltage generating circuit generates a first reference voltage, a second reference voltage, and a reference common-mode voltage according to a post-stage common-mode voltage. The common-mode voltage conversion circuit converts the pre-stage output differential signal into a differential input signal according to the reference common-mode voltage. The common-mode negative feedback circuit generates a control voltage to quickly establish a common-mode negative feedback of the amplifying sub-circuit, wherein the first reference voltage and the second reference voltage are used to cancel a baseline signal of the pre-stage output differential signal. The amplifying circuit can eliminate the baseline signal, convert the common-mode voltage and quickly establish the common-mode negative feedback.

The disclosure relates to an alternating current (AC) coupling circuit including first and second capacitors having first and second input terminals configured to receive an input differential signal and generate an output differential signal at first and second output terminals of the first and second capacitors. The AC coupling circuit further includes a baseline wander correction circuit configured to make the output differential signal resistant to baseline wander due to the input differential signal including one or more time intervals of unbalanced data. The baseline wander correction circuit includes a differential difference amplifier (DDA) having a first differential input configured to receive the input differential signal, a differential output configured to generate a compensation differential signal, and a second differential input configured to receive the compensation differential signal. The compensation differential signal is applied to the output terminals of the first and second capacitors via a pair of resistors, respectively.

A magnetic operational amplifier having a differential stage includes a first magnetic field effect transistor MAGFET and a differential signal conditioner, the differential signal conditioner including a load stage, a differential input pair connected to the load stage and a biasing current source connected to the differential input pair; the magnetic field effect transistor MAGFET being connected to the load stage as a second differential input pair and the differential signal conditioner including a second biasing current source connected to the magnetic field effect transistor MAGFET.

A magnetic operational amplifier having a differential stage includes a first magnetic field effect transistor MAGFET and a differential signal conditioner, the differential signal conditioner including a load stage, a differential input pair connected to the load stage and a biasing current source connected to the differential input pair; the magnetic field effect transistor MAGFET being connected to the load stage as a second differential input pair and the differential signal conditioner including a second biasing current source connected to the magnetic field effect transistor MAGFET.

A two-stage circuit includes a differential-to-single-ended first stage with a differential pair of transistors. The first stage includes a current mirror including a diode-connected transistor having an RC circuit coupled to a drain of the diode-connected transistor. The current mirror is configured to mirror a power supply noise current conducted by the RC circuit through a first stage output terminal to a gate of an output transistor in a second stage of the two-stage circuit.

An amplifying circuit includes a reference voltage generating circuit, a common-mode voltage conversion circuit, a common-mode negative feedback circuit, and an amplifying sub-circuit. The reference voltage generating circuit generates a first reference voltage, a second reference voltage, and a reference common-mode voltage according to a post-stage common-mode voltage. The common-mode voltage conversion circuit converts the pre-stage output differential signal into a differential input signal according to the reference common-mode voltage. The common-mode negative feedback circuit generates a control voltage to quickly establish a common-mode negative feedback of the amplifying sub-circuit, wherein the first reference voltage and the second reference voltage are used to cancel a baseline signal of the pre-stage output differential signal. The amplifying circuit can eliminate the baseline signal, convert the common-mode voltage and quickly establish the common-mode negative feedback.