An exemplary incremental two-step capacitance-to-digital converter (CDC) with a time-domain sigma-delta modulator (TDΔΣM) includes a voltage-controlled oscillator (VCO)-based integrator that can be used in a low-order loop configuration. Example prototypes are disclosed, which when fabricated in 40-nm CMOS technology, provides CDC resolution of 0.29 fF while dissipating only 0.083 nJ per conversion.

The digital-output temperature sensor includes a temperature sensor circuit, a current mirror circuit which makes a mirror current of a temperature detection current flow and pulls in a mirror current of a reference current to thereby output a first difference current from a first output node and output a second difference current from a second output node, a chopping circuit, and an A/D conversion circuit. The chopping circuit performs a chopping operation of making the mirror current of the reference current flow in a second state through a transistor of the current mirror circuit through which the mirror current of the temperature detection current flows in a first state, and making the mirror current of the temperature detection current flow in the second state through the transistor of the current mirror circuit through which the mirror current of the reference current flows in the first state.

A sigma delta modulator comprises an input configured to receive an input analog signal; a summing junction configured to subtract a feedback analog signal from the input analog signal; a first stage including a low pass filter coupled to the summing junction, wherein the low pass filter is configured to generate a first filtered signal; a second stage coupled to the low pass filter, configured to generate a second filtered signal by an active filter; a back-end stage coupled to the second stage, wherein the back-end stage comprises an analog to digital converter configured to convert the 2.sup.nd filtered signal to a digital output signal by sampling at a predetermined sampling frequency(fs); and a feedback path for routing the digital output signal to the summing junction, wherein the feedback path comprises a digital to analog converters, DAC, converting the digital output signal to the feedback analog signal.

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.

An integrated circuit can include an amplifier coupled to receive an analog input signal, an anti-aliasing filter (AAF) coupled to an output of the amplifier, a buffer circuit coupled to an output of the AAF, a sigma-delta modulator configured to generate a digital data stream in response to an output of the buffer, and a plurality of chopping circuits nested within one another, including a first pair of chopping circuits having at least the amplifier disposed therebetween and configured to remove offset in the analog input signal, and a second pair of chopping circuit having at least the first pair of chopping circuits disposed therebetween. The amplifier, AAF, sigma-delta modulator, and chopping circuits can be formed with the same integrated circuit substrate. Corresponding methods and systems are also disclosed.

A calibratable switched-capacitor voltage reference and an associated calibration method are described. The voltage reference includes dynamic diode elements providing diode voltages, input capacitor(s) for sampling input voltages, base-emitter capacitor(s) for sampling one diode voltage with respect to a ground, dynamically trimmable capacitor(s) for sampling the one diode voltage with respect to another diode voltage, and an operational amplifier coupled to the capacitors for providing reference voltage(s) based on the sampled input and diode voltages and on trims of the trimmable capacitor(s). The voltage reference can be configured as a first integrator of a modulator stage of a delta-sigma analog-to-digital converter.

A system and method of replicating and cancelling chopping folding error in delta-sigma modulators. The modulator may include a loop filter coupled to a quantizer providing a digital signal, chopper circuitry that chops analog signals of the loop filter at a chopping frequency, and chopping folding error cancellation circuitry that replicates and cancels a chopping folding error of the chopper circuitry to provide a corrected digital signal. A digital chopper or multiplier chops the digital signal to provide a chopped digital signal, and the chopped digital signal is either amplified or multiplied by a gain value or digitally filtered to replicate the chopping folding error, which is then subtracted from the digital signal for correction. The timing and duty cycle of the chopping frequency may be adjusted. Timing and duty cycle adjustment may be calibrated along with the filtering.

A sigma delta modulator comprises an input configured to receive an input analog signal; a summing junction configured to subtract a feedback analog signal from the input analog signal; a first stage including a low pass filter coupled to the summing junction, wherein the low pass filter is configured to generate a first filtered signal; a second stage coupled to the low pass filter, configured to generate a second filtered signal by an active filter; a back-end stage coupled to the second stage, wherein the back-end stage comprises an analog to digital converter configured to convert the 2.sup.nd filtered signal to a digital output signal by sampling at a predetermined sampling frequency (fs); and a feedback path for routing the digital output signal to the summing junction, wherein the feedback path comprises a digital to analog converters, DAC, converting the digital output signal to the feedback analog signal.

A display device includes a display panel, a noise detection circuit and a processing circuit. The display panel has a touch control function and is configured to detect a contact location of an object to output a touch signal. The noise detection circuit is configured to detect and process a voltage signal of a common electrode of the display panel to output a free run signal and a noise sync signal. The processing circuit is configured to receive the free run signal and the noise sync signal. When the free run signal is at a first level, the processing circuit receives the touch signal in real-time. When the free run signal is at a second level different to the first level, the processing circuit receives the touch signal according to the noise sync signal. The present disclosure also provides a control method for the display device.

A signal processing system may include a signal path and a chop management circuit. The signal path may comprise a chopper configured to chop a differential input signal to the signal path at a chopping frequency and a low-pass filter downstream of the chopper and configured to filter out intermodulation products of a direct current offset of the signal path and intermodulation products of an aggressor on the differential input signal in order to generate an output signal. The chop management circuit may be communicatively coupled to the chopper and configured to, based on operational parameters associated with the signal path, dynamically manage energy of one or more clock signals used to define the chopping frequency.