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 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.

Differential switching output stage for audio, power and digital data transmission can cause a common mode error due to asymmetric transition between positive and negative outputs. Systems and methods are provided for common mode error correction. In particular, summing nodes, novel error amps an edge switching can be used for common-mode feedback (CMFB) in differential signaling and other applications.

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 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 embodiment circuit includes an operational amplifier having a first output terminal and a second output terminal. The circuit further includes a detector coupled between the first output terminal and the second output terminal of the operational amplifier. The detector is configured to detect a common-mode output voltage at the first output terminal and the second output terminal of the operational amplifier. The circuit also includes a feedback amplifier having a first input terminal coupled to the detector and a second input terminal configured to receive a reference voltage. The feedback amplifier is configured to generate a feedback signal based on the common-mode output voltage and the reference voltage and to provide the feedback signal to the operational amplifier. The circuit additionally includes an impedance element having a first terminal coupled to the first input terminal of the feedback amplifier and a second terminal coupled to a supply voltage.

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.

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.

An embodiment circuit includes an operational amplifier having a first output terminal and a second output terminal. The circuit further includes a detector coupled between the first output terminal and the second output terminal of the operational amplifier. The detector is configured to detect a common-mode output voltage at the first output terminal and the second output terminal of the operational amplifier. The circuit also includes a feedback amplifier having a first input terminal coupled to the detector and a second input terminal configured to receive a reference voltage. The feedback amplifier is configured to generate a feedback signal based on the common-mode output voltage and the reference voltage and to provide the feedback signal to the operational amplifier. The circuit additionally includes an impedance element having a first terminal coupled to the first input terminal of the feedback amplifier and a second terminal coupled to a supply voltage.

An analog-to-digital converter (ADC) may include capability to sense and/or compensate for undesired effects when receiving input from a microphone. For example, a sense node may be provided between differential inputs, and that sense node separated from the differential inputs by two or more switches. The sense node may allow for a measurement of an average voltage of the differential inputs. The average voltage may be obtained activating the switches to sample the sampling capacitors coupled to the differential inputs. That average voltage may be used as common mode (CM) data. A controller may receive the CM data, along with differential mode (DM) data, and use the CM and DM data to determine undesired effects, such as DC or AC mismatch at the microphone interface. The controller may then generate a signal for applying compensation to the differential inputs to reduce or eliminate the undesired effects.