A buffer circuit according to an aspect of the inventive concepts include an operational amplifier configured to amplify an input voltage to generate an output voltage; a slew-rate compensating circuit configured to generate a compensation current based on a difference between a voltage level of the input voltage and a voltage level of the output voltage, and configured to provide the compensation current to the operational amplifier through a boosting transistor; and an offset blocking circuit configured to turn off the boosting transistor when the difference between the voltage level of the input voltage and the voltage level of the output voltage is less than a reference voltage level by providing a blocking current to the slew-rate compensating circuit.

A circuit may include a two-stage feedforward compensated operational transconductance integrated amplifier, and the two-stage feedforward compensated operational transconductance integrated amplifier may include an input terminal, an output terminal, a signal path between the input terminal and the output terminal, the signal path comprising a first signal path gain stage and a second signal path gain stage, and ripple rejection circuitry coupled between the input terminal and an intermediate node of the signal path located between the first signal path gain stage and the second signal path gain stage. The ripple rejection circuitry may include a first ripple rejection circuitry gain stage coupled at its input to the input terminal and coupled at its output to an input terminal of a chopper circuit, a notch filter coupled at its input to an output terminal of the chopper circuit, and a second ripple rejection circuitry gain stage coupled at its input to an output terminal of the notch filter and coupled at its output to the intermediate node.

A dc coupled amplifier includes a pre-driver, and amplifier and a bias control circuit. The pre-driver is configured to receive one or more input signals and amplify the one or more input signals to create one or more pre-amplified signals. The amplifier has cascode configured transistors configured to receive and amplify the one or more pre-amplified signals to create one or more amplified signals, the amplifier further having an output driver termination element. The bias control circuit is connected between the pre-driver and the amplifier, the bias control circuit receiving at least one bias current from the output driver termination element of the amplifier, wherein the pre-driver, the amplifier and the bias control circuit are all formed on a same die.

The invention relates to an electrical circuit in the form of a transimpedance amplifier stage, and to a method for operating this circuit. The invention furthermore relates to a circuit containing at least one signal amplifier that has at least one output connection, at least one input connection or at least one pair of differential input connections and at least two voltage supply connections, one of which may also be an earth or ground connection, wherein the signal amplifier has at least one additional connection that is connected internally to at least one of the input connections or the input connection via at least one further component, for example a diode.

The present invention provides a dynamic comparator including a dynamic amplifier and a latch circuit. The dynamic amplifier includes a first input pair, a current source and a gain boosting circuit. The first input pair is configured to receive an input signal to generate an amplified signal at an output terminal. The current source is coupled between the first input pair and a first reference voltage. The gain-boosting circuit is coupled between the first input pair and a second reference voltage, and is configured to receive the input signal to selectively inject current to the output terminal or sink current from the output terminal. The latch circuit is coupled to the dynamic amplifier, and is configured to receive the amplified signal to generate an output signal.

One or more examples relate to an apparatus to amplify differential voltage signal components of voltage across a resistor. Such an apparatus may include a resistor; a differential amplification circuit operatively coupled with the resistor to amplify a differential voltage signal component of a voltage across the resistor; and an operative coupling between the resistor and the differential amplification circuit to pass the differential voltage signal component and isolate a common mode voltage signal component of the voltage across the resistor.

A bandgap reference circuit includes a bandgap reference core circuit that includes a first bipolar transistor having a first emitter current density and a first base-emitter voltage, a second bipolar transistor having a second emitter current density that is smaller than the first emitter current density and having a second base-emitter voltage, a resistor that is connected to the emitter of the second bipolar transistor, and a differential amplifier circuit that is configured to control first and second emitter currents through the first and second bipolar transistors, respectively, such that a sum of the second base-emitter voltage and a voltage drop across the resistor approximates the first base-emitter voltage. The bandgap reference circuit further includes a first replica bipolar transistor that emulates an operating point of the first bipolar transistor and a second replica bipolar transistor that emulates an operating point of the second bipolar transistor.

Apparatus and methods for envelope tracking systems with automatic mode selection are provided herein. In certain configurations, a power amplifier system includes a power amplifier configured to provide amplification to a radio frequency signal and to receive power from a power amplifier supply voltage, and an envelope tracker including a signal bandwidth detection circuit configured to generate a detected bandwidth signal based on processing an envelope signal corresponding to an envelope of the radio frequency signal. The envelope tracker further includes a switch bank configured to receive a plurality of regulated voltages, a filter configured to filter an output of the switch bank to generate the power amplifier supply voltage, and a mode control circuit configured to control a filtering characteristic of the filter based on the detected bandwidth signal.

A signal conversion circuit, a heart rate sensor, and an electronic device are provided, and the signal conversion circuit includes: a photoelectric conversion circuit, configured to convert an optical signal into a current signal; a differential signal conversion circuit, connected to the photoelectric conversion circuit, and configured to convert the current signal into a first differential signal and a second differential signal, where the first differential signal is an integration signal of the current signal in a first phase, and the second differential signal is an integration signal of the current signal in a second phase; and a subtraction amplifier, connected to the differential signal conversion circuit, and configured to amplify a difference value between the first differential signal and the second differential signal, to generate a third differential signal. The signal conversion circuit of embodiments of the present disclosure can effectively suppress ambient interference.

Improved dither detection, measurement, and voltage bias adjustments for an electro-optical modulator are described. The electro-optical modulator generally includes RF electrodes and phase heaters interfaced with semi-conductor waveguides on the arms of Mach-Zehnder interferometers, where a processor is connected to output a bias tuning voltage to the electro-optical modulator for controlling optical modulation. A variable gain amplifier (VGA) can be configured with AC coupling connected to receive a signal from a transimpediance amplifier (TIA) that is configured to amply a photodetector signal from an optical tap that is used to measure an optical signal with a dither signal. The analog to digital converter (ADC) can be connected to receive output from the VGA. The processor can be connected to receive the signal from the ADC and to output the bias tuning voltage based on evaluation of the signal from the tap.