A chopper-stabilized current feedback amplifier includes an input buffer having a non-inverting input and an inverting input. A first group of chopper circuits modulate current at the non-inverting and inverting inputs. The current feedback amplifier further includes a plurality of current mirrors coupled to the input buffer. A second group of chopper circuits modulate current in the current mirrors. The current feedback amplifier also includes phase detector circuitry coupled to the current mirrors and configured to detect a transition current in the current mirrors. The current feedback amplifier also includes a switched capacitor filter having an input coupled to the current mirrors. The switched capacitor filter is turned OFF responsive to the detection of the transition current by the phase detector circuitry. The current feedback amplifier also includes an output stage having an input coupled to the switched capacitor filter and is configured to produce an output signal.

A variable current trans-impedance amplifier (TIA) for an ultrasound device is described. The TIA may be coupled to an ultrasonic transducer to amplify an output signal of the ultrasonic transducer representing an ultrasound signal received by the ultrasonic transducer. During acquisition of the ultrasound signal by the ultrasonic transducer, one or more current sources in the TIA may be varied.

A switched capacitor amplifier circuit includes an operational amplifier, a first capacitor and a second capacitor each having one end connected to a negative input terminal of the operational amplifier, a first switching circuit configured to connect the other end of the first capacitor and a signal source during a first operation, a second switching circuit configured to connect the other end of the second capacitor and the output terminal of the operational amplifier so as to connect the output terminal and the negative input terminal of the operational amplifier through the second capacitor during the second operation, and an impedance converter circuit configured to convert an output impedance of the signal source into a specified impedance, the impedance converter circuit being connected between the first switching circuit and the other end of the first capacitor.

A chopper-stabilized current feedback amplifier includes an input buffer having a non-inverting input and an inverting input. A first group of chopper circuits modulate current at the non-inverting and inverting inputs. The current feedback amplifier further includes a plurality of current mirrors coupled to the input buffer. A second group of chopper circuits modulate current in the current mirrors. The current feedback amplifier also includes phase detector circuitry coupled to the current mirrors and configured to detect a transition current in the current mirrors. The current feedback amplifier also includes a switched capacitor filter having an input coupled to the current mirrors. The switched capacitor filter is turned OFF responsive to the detection of the transition current by the phase detector circuitry. The current feedback amplifier also includes an output stage having an input coupled to the switched capacitor filter and is configured to produce an output signal.

A signal processing circuit, which has a pair of input nodes and a pair of output nodes, includes a first switch pair, a second switch pair, an amplifier, a first compensation capacitor and a second compensation capacitor. The first switch pair is coupled between the pair of input nodes and a plurality of floating nodes. The second switch pair is coupled between the plurality of floating nodes and the pair of output nodes. The amplifier is coupled between the plurality of floating nodes and the pair of output nodes. The first compensation capacitor is coupled between a first floating node among the plurality of floating nodes and a first output node among the pair of output nodes. The second compensation capacitor is coupled between a second floating node among the plurality of floating nodes and the first output node.

An analog computing method includes the steps of: (a) generating a biasing current (IWi) using a constant gm bias circuit operating in the subthreshold region for ultra-low power consumption, wherein gm is generated by PMOS or NMOS transistors, the circuit including a switched capacitor resistor; and (b) multiplying the biasing current by an input voltage using a differential amplifier multiplication circuit to generate an analog voltage output (VOi). In one or more embodiments, the method is used in a vision application, where the biasing current represents a weight in a convolution filter and the input voltage represents a pixel voltage of an acquired image.

A pixel circuit includes a differential amplifier. The differential amplifier includes a non-inverting input terminal, an inverting input terminal, and an output terminal. The differential amplifier includes an input differential pair including first and second NMOS transistors, a current mirror pair including PMOS transistors, and a constant current source including a fifth NMOS transistor. A threshold voltage of each of the first and second NMOS transistors is higher than a threshold voltage of the fifth NMOS transistor. Further, the threshold voltage of each of the first and second NMOS transistors is higher than a threshold voltage of another NMOS transistor.

A chopper amplifier circuit includes a first amplifier path with chopper circuitry, a switched-capacitor filter, and multiple gain stages. The chopper amplifier circuit also includes a second amplifier path with a feed-forward gain stage. A chopping frequency of the chopper circuitry is greater than a threshold frequency at which the second amplifier path is used instead of the first amplifier path.

A readout circuit, for at least one sensing element, includes an amplifier including an input node for receiving charges from the sensing element or elements and an output node, a first feedback loop comprising a feedback capacitor, and at least one second feedback loop comprising another feedback capacitor, between the output and input nodes of the amplifier, for defining different gains. The at least two feedback capacitors being each connectable to a reference voltage supply via respective switches, for pre-loading the feedback capacitors with a predetermined charge different from the charge obtainable from the at least one sensing element, for sampling signals at a reset level before charge transferal. The loops comprising a respective switch between their capacitors and the output node, for operatively connecting and disconnecting each loop, for obtaining reset voltages at two different gains and signal voltages at two different gains.

A chopper amplifier circuit includes a first amplifier path with chopper circuitry, a switched-capacitor filter, and multiple gain stages. The chopper amplifier circuit also includes a second amplifier path with a feed-forward gain stage. A chopping frequency of the chopper circuitry is greater than a threshold frequency at which the second amplifier path is used instead of the first amplifier path.