Methods and apparatuses are provided wherein a sensor which comprises at least two electrodes and a movable part is alternately biased with at least two different voltages.

A device may include a voltage-to-current converter circuit having an operational transconductance amplifier (OTA), the voltage-to-current converter circuit for generating a bias current that is proportional to a reference voltage at a reference voltage input port of the OTA, and a bias current feedback path for providing the bias current to a bias current input port of the OTA. The device may further include a startup current generator circuit coupled to the bias current input port of the OTA, the startup current generator circuit controllable to provide a startup current to the bias current input port during a startup of the device and to be deactivated after the startup of the device.

A rail-to-rail sense amplifier includes a PMOS differential pair and an NMOS differential pair that are arranged in parallel with regard to a biasing network for driving a class AB output stage. The sense amplifier includes a first current differential amplifier and a second current differential amplifier for increasing the output swing while reducing power consumption.

Systems and methods implementing a resonance circuit, including an avalanche photodiode, in which a resonance frequency of the resonance circuit is matched with the frequency of a dynamic biasing signal of the avalanche photodiode, can be used in a variety of applications. In various embodiments, a method for blocking and/or compensating current injection associated with the parasitic capacitance of APDs operated under dynamic biasing may be substantially realized by the matching of the resonance frequency of a resonance circuit including the avalanche photodiode with the frequency of an applied dynamic biasing signal. Additional systems and methods are described that can be used in a variety of applications.

Methods and apparatuses are provided wherein a sensor which comprises at least two electrodes and a movable part is alternately biased with at least two different voltages.

A class AB amplifier with improved DC gain. An amplifier includes an input stage and an output stage. The output stage is configured to amplify an output of the input stage. The output stage includes output transistors, class AB amplifier circuitry, minimum selector circuitry, and gain boost amplifier circuitry. The class AB amplifier circuitry includes a first transistor and a second transistor connected as a differential amplifier. The minimum selector circuitry is configured to control bias current in the output transistors by driving a control input of the first transistor. The gain boost amplifier circuitry is coupled to the class AB amplifier circuitry. The gain boost amplifier circuitry is configured to drive a common mode signal onto the control input of the first transistor and a control input of the second transistor, the common mode signal based on the output of the input stage.

An amplifier circuit, for a capacitive acoustic transducer defining a sensing capacitor that generates a sensing signal as a function of an acoustic signal, has a first input terminal and a second input terminal, which are coupled to the sensing capacitor and: a dummy capacitor, which has a capacitance corresponding to a capacitance at rest of the sensing capacitor and a first terminal connected to the first input terminal; a first amplifier, which is coupled at input to the second input terminal and defines a first differential output of the circuit; a second amplifier, which is coupled at input to a second terminal of the dummy capacitor and defines a second differential output of the circuit; and a feedback stage, which is coupled between the differential outputs and the first input terminal, for feeding back onto the first input terminal a feedback signal, which has an amplitude that is a function of the sensing signal and is in phase opposition with respect thereto.

An electronic circuit for amplifying signals with two components in phase quadrature, which includes: a feedback amplifier with a feedback capacitor; a switch that drives charging and discharging of the feedback capacitor; an additional capacitor; and a coupling circuit, which alternatively connects the additional capacitor in parallel to the feedback capacitor or else decouples the additional capacitor from the feedback capacitor. The switch opens at a first instant, where a first one of the two components assumes a first zero value; the coupling circuit decouples the additional capacitor from the feedback capacitor in a way synchronous with a second instant, where the first component assumes a second zero value.

A bias circuit for a PA. A first transistor has its drain terminal and its gate terminal connected to a first circuit node and its source terminal connected to a first supply terminal, a first current source connected to the first circuit node, and a first resistor connected between the first and second circuit nodes. A second transistor receives a first component of a differential input signal to the PA at its gate terminal, has its drain terminal connected to the second circuit node and its source terminal connected to a second supply terminal, and a third transistor receives a second component of the differential input signal to the PA at its gate terminal, having its drain terminal connected to the second circuit node and its source terminal connected to a second supply terminal. The gates terminals of the second and third transistors are biased by a first voltage.

Various envelope tracking amplifiers are presented that can be switched between an ET (envelope tracking) mode and a non-ET mode. Switches and/or tunable components are utilized in constructing the envelope tracking amplifiers that can be switched between the ET mode and the non-ET mode.