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.

A system may include a front end differential amplifier having two input terminals, two input resistors, each of the two input resistors coupled to a respective one of the two input terminals, and an input common mode biasing circuit for an output stage of the front end differential amplifier, the input common mode biasing circuit comprising two current sources configured to generate currents for biasing the output stage of the front end differential amplifier.

A system may include a front end differential amplifier having two input terminals, two input resistors, each of the two input resistors coupled to a respective one of the two input terminals, and an input common mode biasing circuit for an output stage of the front end differential amplifier, the input common mode biasing circuit comprising two current sources configured to generate currents for biasing the output stage of the front end differential amplifier.

A chopper amplifying circuit employing a negative impedance compensation technique, including a differential input end, a first-level chopper switch, a first-level amplifying circuit, a second-level chopper switch, a second-level amplifying circuit, a negative impedance converting circuit, a negative feedback unit, an input capacitor, and a differential output end, is provided. The differential input end is connected to the first-level chopper switch. An output terminal of the first-level chopper switch is connected to the first-level amplifying circuit through the input capacitor. The first-level amplifying circuit is connected to the second-level chopper switch, which is connected to the second-level amplifying circuit. The second-level amplifying circuit is connected to the differential output end, and is also connected to a feedback input end of the first-level amplifying circuit through the negative feedback unit. The negative impedance converting circuit is parallel-connected to a signal input end of the first-level amplifying circuit.

An amplifier circuit having improved common mode rejection is provided. This can be achieved by estimating the common mode value of an input signal and using this to adjust a target common mode voltage at the output of the amplifier. This can help avoid the differential gain becoming modified by the common mode voltage.

A chopper amplifying circuit employing a negative impedance compensation technique, including a differential input end, a first-level chopper switch, a first-level amplifying circuit, a second-level chopper switch, a second-level amplifying circuit, a negative impedance converting circuit, a negative feedback unit, an input capacitor, and a differential output end, is provided. The differential input end is connected to the first-level chopper switch. An output terminal of the first-level chopper switch is connected to the first-level amplifying circuit through the input capacitor. The first-level amplifying circuit is connected to the second-level chopper switch, which is connected to the second-level amplifying circuit. The second-level amplifying circuit is connected to the differential output end, and is also connected to a feedback input end of the first-level amplifying circuit through the negative feedback unit. The negative impedance converting circuit is parallel-connected to a signal input end of the first-level amplifying circuit.

An amplifier circuit having improved common mode rejection is provided. This can be achieved by estimating the common mode value of an input signal and using this to adjust a target common mode voltage at the output of the amplifier. This can help avoid the differential gain becoming modified by the common mode voltage.

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.

A differential signal conditioner circuit with common mode voltage (CMV) compensation is provided. The circuit includes a signal multiplexer that receives a input signal that includes a high and low signal and a reference CMV signal, a differential amplifier coupled to the signal multiplexer that receives the reference CMV signal and outputs a CMV error value during a first cycle, and receives the input signal and outputs an amplified difference signal during a second cycle. The circuit also includes a CMV measurement circuit that receives the reference CMV signal and outputs a confirmation value during the first cycle, and receives the input signal and outputs a CMV compensation value during the second cycle, and a processing element that receives the CMV error value, the amplified difference signal, the CMV compensation value, and a differential amplifier gain value and generates a CMV compensated output based on the received signals and values.

A differential signal conditioner circuit with common mode voltage (CMV) compensation is provided. The circuit includes a signal multiplexer that receives a input signal that includes a high and low signal and a reference CMV signal, a differential amplifier coupled to the signal multiplexer that receives the reference CMV signal and outputs a CMV error value during a first cycle, and receives the input signal and outputs an amplified difference signal during a second cycle. The circuit also includes a CMV measurement circuit that receives the reference CMV signal and outputs a confirmation value during the first cycle, and receives the input signal and outputs a CMV compensation value during the second cycle, and a processing element that receives the CMV error value, the amplified difference signal, the CMV compensation value, and a differential amplifier gain value and generates a CMV compensated output based on the received signals and values.