In a general aspect, a current sense amplifier circuit (CSA) can include a null amplifier path and a main amplifier path that are both configured to receive a differential input voltage. The null amplifier path can output a first differential output voltage based on the differential input voltage. The main amplifier path can also be configured to receive the first differential output voltage and output a second differential output voltage based on the differential input voltage and the first differential output voltage. The null and main amplifier paths can each include a differential amplifier having first and second input stages that are each configured to receive the differential input voltage. The first input stage and the second input stage of the main amplifier path can and be powered by a respective (first and second) floating voltage supply rails that are referenced to a floating ground rail.

A system includes an amplification circuit and offset calibration circuit. The amplification circuit includes a modulation circuit operable to modulate a received signal, an amplifier operable to amplify the modulated signal, and a modulation circuit operable to demodulate the amplified signal. The offset calibration circuit includes a logic circuit operable to set a control signal and adjust the control signal based on an output of the amplification circuit, where the output is based on the demodulated signal, and a compensation signal generator operable to generate a compensation signal based on the control signal to compensate for an offset associated with the amplification circuit, and apply the compensation signal on the amplification circuit to adjust the output of the amplification circuit. The offset calibration circuit in conjunction with the application circuit reduces flicker, offset, and offset drift, and also suppresses the upmodulate ripple due to chopping.

Disclosed is a differential voltage supplying apparatus configured to supply, to a neural activity recorder, an input signal generated by combining, with a direct current (DC) power supply, a common-mode signal determined from a voltage applied to a detection electrode and a reference electrode connected to the neural activity recorder, and improve a common-mode rejection ratio of the neural activity recorder and generate a DC power supply.

Disclosed is a differential voltage supplying apparatus configured to supply, to a neural activity recorder, an input signal generated by combining, with a direct current (DC) power supply, a common-mode signal determined from a voltage applied to a detection electrode and a reference electrode connected to the neural activity recorder, and improve a common-mode rejection ratio of the neural activity recorder and generate a DC power supply.

A peak detector utilizes two choppers to cancel offset voltage of a transconductance amplifier, so the influence of the offset voltage is preventable and the peak detection accuracy of the peak detector can be improved significantly.

A peak detector utilizes two choppers to cancel offset voltage of a transconductance amplifier, so the influence of the offset voltage is preventable and the peak detection accuracy of the peak detector can be improved significantly.

In a general aspect, a current sense amplifier circuit (CSA) can include a null amplifier path and a main amplifier path that are both configured to receive a differential input voltage. The null amplifier path can output a first differential output voltage based on the differential input voltage. The main amplifier path can also be configured to receive the first differential output voltage and output a second differential output voltage based on the differential input voltage and the first differential output voltage. The null and main amplifier paths can each include a differential amplifier having first and second input stages that are each configured to receive the differential input voltage. The first input stage and the second input stage of the main amplifier path can and be powered by a respective (first and second) floating voltage supply rails that are referenced to a floating ground rail.

In a general aspect, a current sense amplifier circuit (CSA) can include a null amplifier path and a main amplifier path that are both configured to receive a differential input voltage. The null amplifier path can output a first differential output voltage based on the differential input voltage. The main amplifier path can also be configured to receive the first differential output voltage and output a second differential output voltage based on the differential input voltage and the first differential output voltage. The null and main amplifier paths can each include a differential amplifier having first and second input stages that are each configured to receive the differential input voltage. The first input stage and the second input stage of the main amplifier path can and be powered by a respective (first and second) floating voltage supply rails that are referenced to a floating ground rail.

An analog circuit including a pair of input nodes and a pair of output nodes is coupled to a mismatch reduction circuit including an input node, an output node, a phase controller that times even and odd phases, an input switch, and an output switch. The input switch electrically connects the mismatch reduction circuit input node to a first node of the pair of analog circuit input nodes during each even phase and to electrically connects the mismatch reduction circuit input node to a second node of the pair of analog circuit input nodes during each odd phase. The output switch electrically connects a first node of the pair of analog circuit output nodes to the mismatch reduction circuit output node during each even phase and electrically connects a second node of the pair of analog circuit output nodes to the mismatch reduction circuit output node during each odd phase.

A capacitive gain amplifier circuit amplifies an input signal by a pair of differential amplifier circuits couples in series. The first differential amplifier circuit is reset during an autozero phase while disconnected from the second differential amplifier circuit, and the first and second differential amplifier circuits are connected together in series during a chop phase. A set of feedback capacitors is selectively switched in between respective outputs of the second differential amplifier circuit and respective inputs of the first differential amplifier circuit during the chop phase.