A differential pair for an input stage includes two identical branches in parallel, each branch including a first MOS transistor and a second MOS transistor arranged in series, wherein the first transistor and the second transistor have a channel of the same type, and wherein each of the first transistor and the second transistor has a gate coupled to the same corresponding input of the differential pair and a circuit configured to apply to each of the first transistors a potential difference between a source and a channel-forming region of the first transistor.

According to one embodiment, a semiconductor integrated circuit includes first and second power supply lines, first and second nodes, and first and second circuits. The first circuit is configured to supply a first current to the second power supply line, from the first node or the second node. The second circuit is configured to supply a second current from the first power supply line to the first node based on a magnitude of the first current, and to supply a third current from the first power supply line to the second node based on the magnitude of the first current.

Methods, systems, and devices for operating an amplifier with a controllable pull-down capability are described. A memory device may include a memory array and a power circuit that generates an internal signal for components in the memory array. The power circuit may include an amplifier and a power transistor that is coupled with the amplifier. A pull-down capability of the amplifier may be controllable using an external signal that is based on a difference between a reference signal and the internal signal. The power circuit may also include a comparator that is coupled with the amplifier and configured to compare the reference signal and the internal signal. Components of the comparator may be integrated with components of the amplifier, may share a bias circuit, and may use nodes within the amplifier to control the comparator. A signal output by the comparator may control the pull-down capability of the amplifier.

A push-push frequency doubler based on complementary transistors is provided. The first differential amplifier circuit receives a differential input signal having an initial frequency, and amplifies the amplitude of the second harmonic of the differential input signal to obtain a first signal. The second differential amplifier circuit receives the differential input signal with the initial frequency and amplifies the amplitude of the second harmonic of the differential input signal to obtain the second signal. Where, the first signal and the second signal are a set of differential signals with the same amplitude and a phase difference of 180°. The output load circuit extracts the second harmonic signal in the first and second signal respectively to obtain and output a pair of differential output signal with first output frequency whose value is twice of the initial frequency. As a result, the frequency doubler with differential output signal is realized.

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. The variable-current trans-impedance amplifier may include multiple stages, including a first stage having N-P transistor pairs configured to receive an input signal and produce a single-ended amplified signal.

An operational amplifier includes a single-stage amplifier and a current controller. The single-stage amplifier receives an input signal, and amplifies the input signal to generate an output signal, wherein the single-stage amplifier includes a voltage controlled current source circuit that operates in response to a bias voltage input. The current controller receives the input signal, and generates the bias voltage input according to the input signal. The bias voltage input includes a first bias voltage, a second bias voltage, a third bias voltage, and a fourth bias voltage. None of the first bias voltage, the second bias voltage, the third bias voltage, and the fourth bias voltage is directly set by the input signal of the single-stage amplifier.

Techniques for interpolating two voltages without loading them and without requiring significant power or additional area are described. The techniques include specific topologies for the buffering amplifiers that offer accuracy by cancelling systematic error sources without relying on high gain, thus simplifying the frequency compensation, and reducing power consumption. This can be achieved by biasing the amplifiers from the load current by an innovative feedback structure, which can remove the need for high impedance nodes inside the amplifiers.

An amplifier includes a first amplification circuit, a second amplification circuit including first and second amplification transistors controlled by the first amplification circuit to generate first and second output signals and a bias transistor turned on based on a bias signal to generate the first output signal, a filter circuit including a bias capacitor connected to the first amplification transistor and the bias transistor to generate the first bias signal using a first bias voltage, and a feedback circuit configured to receive the first and second output signals and output a feedback signal that adjusts an average of the first and second output signals to correspond to a reference signal, to the first amplifier. The filter circuit adjusts a voltage of the bias capacitor such that a voltage of the bias capacitor when the amplifier is disabled corresponds to a voltage of the bias capacitor when the amplifier is enabled.

A self-bias signal generating circuit includes a differential amplifier circuit including a current source transistor. The differential amplifier circuit is configured to amplify at least a pair of differential input signals to generate at least a pair of differential output signals, and the differential amplifier circuit is configured to generate an output common-mode signal based on the at least a pair of differential output signals. The self-bias signal generating circuit includes a feedback loop circuit configured to adjust a voltage level of the output common-mode signal to generate a self-bias signal, and the feedback loop circuit is configured to provide the self-bias signal to the differential amplifier circuit. The self-bias signal is applied to a gate terminal of the current source transistor.

Provided herein are apparatus and methods for a multi-stage signal-processing circuit. The signal-processing circuit can include multiple configurable stages that can be cascaded and configured to process an input signal. Control circuitry can be used to select an output of the configurable stages. Serial data can be recovered with good signal integrity using a signal monitor with the configurable stages by virtually placing the signal monitor on a buffered output node.