A transconductor circuitry (10) with adaptive biasing comprises a first input terminal (ElOa) to apply a first input signal (inp), and a second input terminal (ElOb) to apply a second input signal (inn). A control circuit (200) is configured to control a first controllable current source (110) in a first current path (101) and a second controllable current source (120) in a second current path (102) in response to at least one of a first potential of a first node (N1) of the first current path (101) and a second potential of a second node (N2) of the second current path (102). The first node (N1) is located between a first transistor (150) and the first controllable current source (110), and the second node (N2) is located between a second transistor (160) and the second controllable current source (120).

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.

An operational amplifier with one or more fully-differential amplifier stages has a common-mode control input. A low-frequency feedback control path is coupled between an output of the fully-differential amplifier stages and the common-mode control input to control low-frequency drift of the common-mode voltage of the output of the stages. A high-frequency feed-forward control path couples a pair of inputs of the stages to control high-frequency ripple of a common-mode voltage of the inputs of the stages. One or more of the differential amplifier stages may have a bias input that controls a direct-current (DC) bias voltage of gates of pull-up transistors of the stage that is both DC and capacitively coupled to the gates so that the stage operates with class A bias at DC and with class AB bias at high frequencies.

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.

An operational amplifier with one or more fully-differential amplifier stages has a common-mode control input. A low-frequency feedback control path is coupled between an output of the fully-differential amplifier stages and the common-mode control input to control low-frequency drift of the common-mode voltage of the output of the stages. A high-frequency feed-forward control path couples a pair of inputs of the stages to control high-frequency ripple of a common-mode voltage of the inputs of the stages. One or more of the differential amplifier stages may have a bias input that controls a direct-current (DC) bias voltage of gates of pull-up transistors of the stage that is both DC and capacitively coupled to the gates so that the stage operates with class A bias at DC and with class AB bias at high frequencies.

Circuitry for voltage-to-current conversion, and in particular to differential voltage-to-current conversion circuitry. Such circuitry is operable to receive a differential voltage input signal and output a corresponding differential current signal. First and second controllable current sinks are connected to first and second load nodes of the circuitry so as to draw corresponding sink currents from those nodes.

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.

In at least one embodiment, a fully differential amplifier is provided. A first amplifying circuit receives a first input voltage signal and provides a first output voltage signal. A second amplifying circuit to receive a second voltage signal and to provide a second output voltage signal. A summing circuit to provide a common mode component of the first input voltage signal and the second input voltage signal. A compensation circuit to amplify the common mode component of the first input voltage signal and the second input voltage signal and output an injection signal. A common gain setting network including a plurality of resistors to receive the injection signal and to interface with the first amplifying circuit, the second amplifying circuit, and the compensation circuit to prevent the common mode component from being present in the first output voltage signal and the second output voltage signal.

The present invention relates to circuitry for voltage-to-current conversion, and in particular to differential voltage-to-current conversion circuitry. Such circuitry is operable to receive a differential voltage input signal and output a corresponding differential current signal.

Systems and methods of the disclosed subject matter for converting light into electrical signals are provided including receiving light input and outputting electrical signals proportional to the light input with a sensor, increasing a transimpedance gain of an amplifier to amplify the electrical signals with a T-network of resistors coupled to the amplifier and the sensor, filtering the electrical signals with a filter circuit coupled to the amplifier and the T-network of resistors to increase noise rejection in a predetermined frequency range, and outputting the filtered electrical signals.