An operational amplifier comprises: a first amplifier stage 4 comprising a first differential pair of transistors 8, 10 arranged to receive and amplify a differential input signal 18, 20 thereby providing a first differential output signal 22, 24; and a second amplifier stage 6 comprising a second differential pair of transistors 26, 28 arranged to receive and amplify the first differential output signal 22, 24 thereby providing a second differential output signal 38, 40.

Methods and systems for accurate gain adjustment of a transimpedance amplifier using a dual replica and servo loop is disclosed and may include, in a transimpedance amplifier (TIA) circuit comprising a first TIA, a second TIA, and a third TIA, each comprising a configurable feedback impedance, and a control loop, where the control loop comprises a gain stage with inputs coupled to outputs of the first and second TIAs and an output coupled to the configurable feedback impedance of the second and third TIAs: configuring a gain level of the first TIA by configuring its feedback impedance, configuring a gain level of the third TIA by configuring a reference current applied to an input of the first TIA, and amplifying a received electrical signal to generate an output voltage utilizing the third TIA. The reference current may generate a reference voltage at one of the inputs of the gain stage.

Systems and methods relate to providing a transmit signal. The transmit signal can be provided in a transmitter circuit including a main pre-equalizer, a main power amplifier in communication with the main pre-equalizer, a replica pre-equalizer, and a replica power amplifier in communication with the replica pre-equalizer. The replica preamplifier is in communication with the main pre-equalizer, and control signals are provided to the main pre-equalizer to reduce distortion. The control signals are provided in response to an output signal of the replica power amplifier.

A circuit can include a first current source, a second current source, and a differential inverter amplifier electrically coupled between the first current source and the second current source. The differential inverter amplifier can include a plurality of load resistors and a plurality of diode-connected metal oxide semiconductor (MOS) clamps configured to limit output swing and minimize common mode disturbances.

The current-to-voltage converter includes an input for the current to be converted, an output for the converted voltage, a current-to-voltage conversion resistor arranged between the output and a reference potential, a processing circuit including a transistor, the input being connected to the output via the transistor, a twin circuit including components identical to and disposed in a similar way to those of the processing circuit, a voltage follower connected at the input to the processing circuit and at the output to the twin circuit, and means for reinjecting the current at the output of the follower into the processing circuit.

An amplifier circuit a differential input stage coupled to a first input and to a second input between which a differential input voltage is present. A converter stage is coupled to the input stage to convert the differential input voltage into a converted voltage. An output stage is coupled to the converter stage and generates, starting from the converted voltage, an output voltage on a single output of the amplifier circuit. A biasing stage is coupled to the input stage and to the output stage to supply a biasing current. A chopper module reduces a contribution of offset and noise associated with the output voltage. The chopper module is coupled to the input stage, converter stage, and to the biasing stage. The chopper module includes an input chopper stage, a converter chopper stage, and a biasing chopper stage that operate jointly under control of a chopper signal.

An ultrasonic probe includes: an ultrasonic transducer; an amplification stage; a bias circuit, which determines a bias voltage on an input terminal of the amplification stage; and a selector having an intermediate node, a high-voltage switch between the intermediate node and the transducer, and a first low-voltage switch between the intermediate node and the input terminal. A control unit controls the high-voltage switch and the first low-voltage switch so as to alternately couple and decouple the amplification stage and the transducer. A precharge circuit determines a precharge voltage on the intermediate node as a function of the bias voltage, before the amplification stage and the transducer are coupled.

A semiconductor device may include a substrate, active circuitry on the substrate and including differential transistor pairs, and threshold voltage test circuitry on the substrate. The threshold voltage test circuitry may include a pair of differential test transistors replicating the differential transistor pairs within the active circuitry, with each test transistor having a respective input and output, and at least one gain stage configured to amplify a difference between the outputs of the differential test transistors for measuring a threshold voltage thereof. The differential transistor pairs and the pair of differential test transistors may each include spaced apart source and drain regions, a channel region extending between the source and drain regions, and a gate overlying the channel region. Each of the channel regions may include a superlattice.

An amplifier may include a differential pair circuit configured to generate an output signal according to a first input signal and a second input signal, a plurality of current sinks coupled between a ground terminal and the differential pair circuit, and a feedback circuit configured to sense a level of the output signal and generate a feedback signal. At least one of the plurality of current sinks is controlled according to the feedback signal.

A circuit may include amplifier circuitry configured to receive a current signal at an amplifier input node, convert the current signal to a voltage signal, and output the voltage signal at an amplifier output node. The circuit may also include overload circuitry configured to receive a replica DC input voltage and a replica DC output voltage. The overload circuitry may be further configured to detect that the current signal exceeds a threshold level based on the replica DC input voltage and the replica DC output voltage. In addition, the overload circuitry may be configured to, in response to and based on detecting that the current signal exceeds the threshold level, direct DC current of the current signal through a DC shunt path and direct AC current of the current signal through an AC shunt path. The AC shunt path may be different from the DC shunt path.