A detection device includes: a detector including first electrodes and second electrodes disposed around a the first electrodes; a detection circuit configured to detect proximity of an external object to the detector; a power circuit configured to generate a square wave; and a filter that is coupled to the power circuit through an isolator and configured to receive the square wave transmitted through the isolator. The filter includes a low-pass filter circuit and a digital potentiometer. A periodically oscillating potential based on output from the filter is provided as a reference potential of the power circuit and provided to the second electrodes. A reference potential of the filter is a fixed potential. The power circuit can change the frequency of the generated square wave. The filter can change the frequency of the periodically oscillating potential in accordance with an electric resistance value of the digital potentiometer.

A circuit having an input and an output, the circuit comprising: a first amplifier having a first input, a second input and an output coupled to the output of the circuit; a first capacitor having a first terminal coupled to the first input of the first amplifier and a second terminal coupled to the output of the first amplifier; a first resistor having a first terminal coupled to the first input of the first amplifier and a second terminal; a buffer having an output coupled to the second terminal of the first resistor and an input; a second resistor having a first terminal coupled to the output of the first amplifier and a second terminal coupled to the input of the buffer; a second capacitor coupled between the input of the buffer and ground; and a third resistor coupled between the input of the buffer and the input of the circuit.

A circuit having an input and an output, the circuit comprising: a first amplifier having a first input, a second input and an output coupled to the output of the circuit; a first capacitor having a first terminal coupled to the first input of the first amplifier and a second terminal coupled to the output of the first amplifier; a first resistor having a first terminal coupled to the first input of the first amplifier and a second terminal; a buffer having an output coupled to the second terminal of the first resistor and an input; a second resistor having a first terminal coupled to the output of the first amplifier and a second terminal coupled to the input of the buffer; a second capacitor coupled between the input of the buffer and ground; and a third resistor coupled between the input of the buffer and the input of the circuit.

A sensor apparatus includes a resonator, a transducer, a damping resistor, a first switch, a filter stage, a second switch, and a noise rejection stage. The transducer is configured to detect a position of the resonator. The damping resistor is configured to electrostatically actuate the transducer and convert a thermomechanical noise of the resonator to an electromechanical noise. The first switch is configured to receive a first signal from the transducer. The filter stage is configured to receive the first signal and adjust a phase and a gain of the first signal and output a filtered first signal. The second switch is configured to receive a second signal from the transducer. The noise rejection stage is configured to receive the filtered first signal and the second signal and reduce the filtered first signal from an output signal.

A circuit having an input and an output, the circuit comprising: a first amplifier having a first input, a second input and an output coupled to the output of the circuit; a first capacitor having a first terminal coupled to the first input of the first amplifier and a second terminal coupled to the output of the first amplifier; a first resistor having a first terminal coupled to the first input of the first amplifier and a second terminal; a buffer having an output coupled to the second terminal of the first resistor and an input; a second resistor having a first terminal coupled to the output of the first amplifier and a second terminal coupled to the input of the buffer; a second capacitor coupled between the input of the buffer and ground; and a third resistor coupled between the input of the buffer and the input of the circuit.

An active filter and an analog-to-digital converter (ADC) configured to suppress out-of-band peaking. An active filter may include an active device configured to provide a power gain to an input signal, a feedback network configured to connect an output of the active device to an input of the active device, and an input impedance network configured to couple the input signal to the input of the active device. A combination of the feedback network and the input impedance network is configured to provide frequency response properties of the active filter such that a frequency domain signal transfer function of the active filter has a constant in numerator.

A filter can perform two filtering processes. The filter includes a switching circuit, a first filter circuit, and a second filter circuit. The first filter circuit is coupled to the switching circuit. The second filter circuit is coupled to the switching circuit. The first filter circuit performs a first filtering process on an input signal according to a state of the switching circuit. The first filter circuit and the second filter circuit work together to perform a second filtering process on the input signal according to the state of the switching circuit.

Circuits and methods are disclosed that, in embodiments, may be used for low power memory signal readout. In an embodiment, the circuit comprises a front end stage including an impedance conversion network for receiving a signal and providing voltage or current gain, and a wideband multiplier for receiving an output signal from the impedance conversion network and converting the output signal to differential output signals; and a baseband stage including a voltage mode mixer for receiving the differential output signals from the wideband multiplier and providing voltage gain, and a bandpass filter/amplifier for receiving a mixer output signal from the voltage mode mixer and filtering and amplifying the mixer output signal; and wherein DC voltages of the front-end stage are biased independently of a biasing of DC voltages of the baseband stage.

A filter includes a switching circuit, a first filter circuit, and a second filter circuit. The first filter circuit is coupled to the switching circuit. The second filter circuit is coupled to the switching circuit. The switching circuit is controlled to control the first filter circuit to perform a first filtering process on an input signal or control the first filter circuit to work in coordination with the second filter circuit to perform a second filtering process on the input signal.

Systems and methods for improving source-follower-based Sallen-Key architectures are disclosed. In particular, systems and methods for circumventing the non-idealities associated with source-follower-based Sallen-Key biquad filters when used in either baseband signal or radiofrequency paths. The systems and methods disclosed herein present power-efficient, cost-efficient solutions that can be implemented in a reduced area of a circuit.