Disclosed herein is a circuit including a differential amplifier having a pair of input transistors coupled in a differential arrangement between adjustable current sources and receiving input differential signals from a pair of input voltage regulators. The adjustable current sources are configured to source more current to the pair of input transistors than current that is sunk from the pair of input transistors. A first amplifier has inputs coupled to receive differential output voltages from the differential amplifier. A second amplifier has inputs coupled to receive amplified differential output voltages from the first amplifier. A low pass filter has inputs coupled to receive further amplified differential output voltages from the second amplifier and produce final differential output voltages.

The present invention provides a circuit having a filter with an amplifier circuit for filtering and amplifying an input signal to generate an output signal, wherein a corner frequency of the filter is adjustable to control a settling time of the output signal.

Signal quality is improved in a circuit for amplifying and sampling an analog signal. An input signal is input to one end of an input-side resistor. An operational amplifier amplifies the input signal, and outputs the input signal from an output terminal as an amplified signal. One end of a filter capacitor is connected to an input terminal of the operational amplifier. A predetermined frequency component of the input signal passes through the filter capacitor. A sampling capacitor imports the amplified signal during a predetermined sampling period, and holds the amplified signal during a predetermined hold period. A sampling switch connects the output terminal of the operational amplifier to one end of the sampling capacitor during the sampling period, and disconnects the output terminal of the operational amplifier from one end of the sampling capacitor during the hold period. A cutoff circuit disconnects the input-side resistor from one end of the filter capacitor during the sampling period, and connects the input-side resistor to one end of the filter capacitor during the hold period.

Systems and methods are provided for improved noise performance of audio amplifiers. In one example, a system includes a multistage amplifier comprising at least a first stage amplifier and a second stage amplifier. The system further includes a plurality of switches disposed within the multistage amplifier to configure the multistage amplifier. The system further includes a control signal configured to control the multistage amplifier to a normal amplification mode or a mute state, wherein the multistage amplifier is adapted to amplify an input signal in the normal amplification mode, the multistage amplifier is adapted to output a zero signal in the mute state, and internal amplification stages of the multistage amplifier are disabled in the mute state, and output stages of each of the at least first stage amplifier and the second stage amplifier are electrically shorted and/or shorted to a fixed bias voltage in the mute state.

A calibration circuit configured to calibrate a signal of a sensing unit comprises: an amplifier, a first impedance element and a second impedance element. The amplifier has a first input terminal, a second input terminal and an output terminal. The first input terminal is coupled to a first terminal of the sensing unit, the second input terminal is coupled to a reference voltage, and the output terminal is feedback to the first input terminal and outputs the readout signal. A first terminal of the first impedance element is coupled to the first input terminal of the amplifier, and a second terminal of the first impedance element is coupled to a calibration voltage. A first terminal of the second impedance element is coupled to the first terminal of the first impedance element, and a second terminal of the second impedance element is coupled to the output terminal of the amplifier.

Systems and methods are provided for improved noise performance of audio amplifiers. In one example, a system includes a multistage amplifier comprising at least a first stage amplifier and a second stage amplifier. The system further includes a plurality of switches disposed within the multistage amplifier to configure the multistage amplifier. The system further includes a control signal configured to control the multistage amplifier to a normal amplification mode or a mute state, wherein the multistage amplifier is adapted to amplify an input signal in the normal amplification mode, the multistage amplifier is adapted to output a zero signal in the mute state, and internal amplification stages of the multistage amplifier are disabled in the mute state, and output stages of each of the at least first stage amplifier and the second stage amplifier are electrically shorted and/or shorted to a fixed bias voltage in the mute state.

A tuning fork sensor system places a controlled bias on the proof-mass drive-axis electrodes to cancel the quadrature charge. Also, its charge amplifiers employ a field-effect transistor biased slightly into the triode region so that it behaves as a very large value resistor. In addition, it uses a phase-locked loop having a special loop filter in order to optimize performance by rejecting off-frequency drive feedthrough to the motor pick-off while resulting in very low phase wander for the demodulation references.

A novel comparison circuit, a novel amplifier circuit, a novel battery control circuit, a novel battery protection circuit, a power storage device, a semiconductor device, an electronic device, and the like are provided. The semiconductor device includes a capacitor, a first amplifier circuit including a first output terminal electrically connected to a first electrode of the capacitor, and a second amplifier circuit including an input terminal, a second output terminal, a first transistor, and a second transistor; a second electrode of the capacitor is electrically connected to the input terminal; the input terminal is electrically connected to a gate of the first transistor and one of a source and a drain of the second transistor; one of a source and a drain of the first transistor is electrically connected to the second output terminal; the second transistor has a function of supplying a potential to the input terminal and holding the potential; and a channel formation region of the second transistor includes a metal oxide containing at least one of indium and gallium.

An amplification apparatus includes an amplifier having an inverting terminal, and a non-inverting terminal connected to a reset voltage node, a first capacitor connected to the inverting terminal, an input voltage being applied to the first capacitor, a second capacitor connected to the inverting terminal and an output terminal of the amplifier, and a duty-cycled resistor, connected in parallel to the second capacitor, including a first resistor. The duty-cycled resistor is configured to connect the first resistor and the inverting terminal and to disconnect the first resistor and the reset voltage node during a first time interval included in a period to complete an on-and-off cycle of the duty-cycled resistor, and disconnect the first resistor and the inverting terminal and to connect the first resistor and the reset voltage node during a second time interval included in the period.

An embodiment of this disclosure provides an automated payment apparatus. The apparatus includes a photodiode current integrator configured to charge an integration capacitor. The photodiode current integrator includes a first feedback resistor connected along a negative feedback path of an operational amplifier between an output of the operational amplifier and a negative input of the operational amplifier. The photodiode current integrator also includes a second feedback resistor connected along a positive feedback path of the operational amplifier between the output of the operational amplifier and a positive input of the operational amplifier. The photodiode current integrator also includes an integration capacitor connected to the positive input of the operational amplifier and to common circuit ground. The photodiode current integrator also includes a reset switch connected to the positive input of the operational amplifier and to common circuit ground or to additional voltage source. The photodiode current integrator also includes a photodiode connected to the positive input and the negative input of the operational amplifier.