A filter circuit includes a filter and a current mode programmable gain amplifier, where the filter circuit is configured to filter an input signal to obtain an output signal. The filter is supplied with the input signal. The filter comprises at least one current extraction element configured to extract a first output current signal. The current mode programmable gain amplifier is configured to receive and amplify the first output current signal to obtain an amplified current signal. The output signal is derived from the amplified current signal.

The disclosure relates to technology for a fully differential adjustable gain device that includes differential input terminals, differential output terminals, fully differential signal processing circuitry, and first and second cross-coupled segments. The first cross-coupled segment is coupled between differential input terminals of the fully differential adjustable gain device and a negative input of the fully differential signal processing circuitry. The second cross-coupled segment is coupled between differential input terminals of the fully differential adjustable gain device and a positive input of the fully differential signal processing circuitry. The fully differential adjustable gain device has a gain that is adjustable by adjusting values of the first and second cross-coupled segments, while maintaining a substantially consistent frequency response and a substantially consistent input impedance of the fully differential adjustable gain device, so long as a specified relationship between values of the first and second cross-coupled segments is kept substantially constant.

An active filter comprising an operational amplifier, and a controller configured to control the bandwidth of the operational amplifier based on a filter cutoff frequency setting and/or a noise performance setting.

A sensor device includes: first sensors; second sensors which form capacitances with the first sensors; a sensor transmitter connected to the first sensors, where the sensor transmitter supplies driving signals to the first sensors; and a sensor receiver connected to the second sensors, where the sensor receiver receives sensing signals from the second sensors, and the sensor receiver includes a band pass filter which filters the sensing signals. The band pass filter includes: a first integrator including a first amplifier; a first high pass filter converter connected to a first input terminal, a second input terminal and a first output terminal of the first amplifier, where the first high pass filter converter time-divisionally provides N high pass filter conversion paths; and a first gain auxiliary component connected to the first input terminal and the first output terminal of the first amplifier while the first integrator performs an integral function.

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 device and a circuit arrangement comprising an active filter device are disclosed. In an embodiment the active filter device includes sensor terminals for applying a sensor signal depending on a sensed noise signal, an output terminal for providing a correction signal that is suitable for reducing the noise signal, a signal source adapted for generating a correction signal and a high-pass filter coupled between the sensor terminals and the signal source, wherein the correction signal is generated with a dependence on a high-pass filtered sensor signal.

A programmable band-pass filter circuit, which is included by an analog front-end circuit and used for capacitance detection, includes an operational amplifier, an input resistor, a feedback resistor, and a feedback capacitor. The operational amplifier includes a first input coupled to a reference level, a second input, and an output. The input resistor has a first end coupled to a sensed capacitor and a second end coupled to the second input of the operational amplifier. The feedback resistor and feedback capacitor are connected between the second input of the operational amplifier and the output of the operational amplifier, respectively.

A delta-sigma modulator may comprise a loop filter for integrating and outputting a difference between an input signal and an analog signal; a quantizer for quantizing and outputting a signal output from the loop filter; and a digital-to-analog converter (DAC) for outputting the analog signal by digital-to-analog converting a signal output from the quantizer. Also, the loop filter may comprise an operational amplifier; and a circuit including at least one capacitor, at least one resistor, and at least one switch which are connected to the operational amplifier. Also, signal transfer characteristics of the loop filter satisfy a third-order transfer function or a second-order transfer function by turning on or off the at least one switch.

A delta-sigma modulator may comprise a loop filter for integrating and outputting a difference between an input signal and an analog signal; a quantizer for quantizing and outputting a signal output from the loop filter; and a digital-to-analog converter (DAC) for outputting the analog signal by digital-to-analog converting a signal output from the quantizer. Also, the loop filter may comprise an operational amplifier; and a circuit including at least one capacitor, at least one resistor, and at least one switch which are connected to the operational amplifier. Also, signal transfer characteristics of the loop filter satisfy a third-order transfer function or a second-order transfer function by turning on or off the at least one switch.

Provided is a wireless communication receiver including an antenna for receiving an RF signal; a first mixer, coupled to the antenna, for performing frequency conversion on the RF signal from the antenna by mixing the RF signal with a local oscillator signal to provide a first intermediate frequency (IF) signal; and a first filter, coupled to the first mixer, configured to pass a predetermined band of frequencies of the first IF signal and to generate a first channel signal. The first filter includes a negative feedback loop coupled to the first mixer for performing negative feedback loop control on the first IF signal; and a positive capacitive feedback loop coupled to the first mixer for performing positive capacitive feedback loop control on the first IF signal, the negative feedback loop and the positive capacitive feedback loop being coupled in parallel.