An amplifier circuit includes a resistor divider (R.sub.REF) comprising n resistive elements, two main nodes defined at each end thereof, two readout nodes (d.sub.1, d.sub.2), resistor nodes (q) defined between adjacent resistive elements, and an input current source (I.sub.REF) connected or connectable to the first main node (a). The resistor divider (R.sub.REF) comprises two arrays of addressable switch elements controllable by a feedback signal (s.sub.FB) to be open or closed. The amplifier circuit includes a differential pair of transistors (T.sub.1, T.sub.2), wherein source terminals of each of the transistors (T.sub.1, T.sub.2) are connected to the second node (b), gate terminals of the transistors (T.sub.1, T.sub.2) are connected to input signals (v.sub.1, v.sub.2), drain terminals of the transistors (T.sub.1, T.sub.2) are connected to current sources (I.sub.1, I.sub.2), and bulk terminals of the transistors (T.sub.1, T.sub.2) are connected to the readout nodes (d.sub.1, d.sub.2). The amplifier circuit functions as a difference amplifier, wherein the bulk terminals affect a threshold of the respective transistors (T.sub.1, T.sub.2) so as to add or subtract a differential signal derived from the readout nodes (d.sub.1, d.sub.2) of the resistor divider (R.sub.REF) determined by the feedback signal (s.sub.FB).

A circuit which reuses current to synthesize a negative impedance includes a current source circuit, a differential circuit, and a negative impedance conversion circuit. The current source circuit is arranged to provide at least one predetermined current, wherein the current source circuit has a first connection port and a second connection port, and the first connection port of the current source is coupled to a first reference voltage. The differential circuit is coupled between the second connection port of the current source circuit and a second reference voltage, and is arranged to receive a differential input pair and generate a differential output pair, wherein the differential circuit has a differential output port. The negative impedance conversion circuit is coupled between the differential output port and a third reference voltage, wherein the third reference voltage is different from the first reference voltage.

An output buffer circuit includes an operational amplifier configured to generate an amplifier output voltage signal based on an input voltage signal and on a compensation current, a slew rate compensating circuit configured to generate the compensation current to increase a slew rate of the amplifier output voltage signal based on a difference between the input voltage signal and a feedback voltage signal, an output path circuit connected between the operational amplifier and an output pad, the output path circuit configured to transfer the amplifier output voltage signal to generate a pad output voltage signal through the output pad, and a feedback path circuit, the feedback path circuit connected between the slew rate compensating circuit and a feedback input node that is on the output path circuit, the feedback path circuit configured to generate the feedback voltage signal.

A circuit which reuses current to synthesize a negative impedance includes a current source circuit, a differential circuit, and a negative impedance conversion circuit. The current source circuit is arranged to provide at least one predetermined current, wherein the current source circuit has a first connection port and a second connection port, and the first connection port of the current source is coupled to a first reference voltage. The differential circuit is coupled between the second connection port of the current source circuit and a second reference voltage, and is arranged to receive a differential input pair and generate a differential output pair, wherein the differential circuit has a differential output port. The negative impedance conversion circuit is coupled between the differential output port and a third reference voltage, wherein the third reference voltage is different from the first reference voltage.

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.

An output buffer circuit includes an operational amplifier configured to generate an amplifier output voltage signal based on an input voltage signal and on a compensation current, a slew rate compensating circuit configured to generate the compensation current to increase a slew rate of the amplifier output voltage signal based on a difference between the input voltage signal and a feedback voltage signal, an output path circuit connected between the operational amplifier and an output pad, the output path circuit configured to transfer the amplifier output voltage signal to generate a pad output voltage signal through the output pad, and a feedback path circuit, the feedback path circuit connected between the slew rate compensating circuit and a feedback input node that is on the output path circuit, the feedback path circuit configured to generate the feedback voltage 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 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 voltage regulator includes an error amplifier which receives a feedback voltage and a reference voltage and thereby controls a gate voltage of an output transistor, a non-regulation detection circuit having a differential amplifier circuit operating on a current corresponding to an output current of the output transistor, and an overshoot suppression circuit having an overshoot detection circuit which enables an overshoot detection by a signal indicating the detection of non-regulation state from the non-regulation detection circuit.

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.