A sigma delta (SD) pulse-width modulation (PWM) loop includes a loop filter implementing a linear transfer function to generate a loop filter signal, wherein the loop filter is configured to receive an input signal and a first feedback signal and generate the loop filter signal based on the input signal, the first feedback signal, and the linear transfer function; and a hysteresis comparator coupled to an output of the loop filter, the hysteresis comparator configured to receive the loop filter signal and generate a sigma delta PWM signal based on the loop filter signal, wherein the first feedback signal is derived from the sigma delta PWM signal.

The present invention provides a fractional-N frequency synthesizer comprising a divider controller comprising a multistage noise Shaping (MASH) digital delta-sigma modulator comprising L error feedback modulator (EFM) stages, wherein the jth EFM stage is configured to receive as an input the sum of the error of the preceding EFM stage and a high amplitude dither signal derived from the error of the kth EFM stage, where 1≤j≤k≤L.

A delta-sigma modulator includes a quantizer, a signal propagation path including a plurality of cascaded integrators coupled between the input node and the quantizer, and a feedback network including a plurality of digital-to-analog converters. In a calibration mode of operation, a first digital-to-analog converter of the plurality of digital-to-analog converters of the feedback network receives a signal including a periodic alternated digital sequence, the first digital-to-analog converter being coupled to a first integrator of the plurality of cascaded integrators, integrators of the plurality of cascaded integrators other than the first integrator operate in a gain mode of operation, the delta-sigma modulator generates a digital test signal at an output of the quantizer based on the signal including the periodic alternated digital sequence, and calibration circuitry generates a calibration signal based on the digital test signal and a reference digital word.

A sigma delta (SD) pulse-width modulation (PWM) loop includes a loop filter implementing a linear transfer function to generate a loop filter signal, wherein the loop filter is configured to receive an input signal and a first feedback signal and generate the loop filter signal based on the input signal, the first feedback signal, and the linear transfer function; and a hysteresis comparator coupled to an output of the loop filter, the hysteresis comparator configured to receive the loop filter signal and generate a sigma delta PWM signal based on the loop filter signal, wherein the first feedback signal is derived from the sigma delta PWM signal.

A digital control circuitry for a MEMS gyroscope is provided. The digital control circuitry comprises a digital primary loop circuitry configured to process a digitized primary signal, a digital secondary loop circuitry configured to process a digitized secondary signal and a digital phase shifting filter circuitry configured to generate two phase shifted demodulation signals from the digitized primary signal. The digital secondary loop is configured to demodulate the digitized secondary signal using the two phase shifted demodulation signals.

Systems and method for improving stability and performance in class-D modulators. In particular, a multi-cycle feedback network is positioned around a quantizer of a digital class-D amplifier. The multi-cycle feedback network allows the main class-D feedback loop to have multiple clock cycles of delay.

A data converter is disclosed. The data converter includes a loop-filter, a quantizer, an analog dynamic element matching (DEM) shuffler, a digital DEM shuffler and a feedback digital-to-analog converter. The loop-filter receives analog signals from an analog input. The quantizer then converts the filtered analog signals from the loop-filter to digital signals at a digital output. The analog DEM shuffler shuffles a set of analog threshold levels of the quantizer to yield a set of partially shuffled digital data at an output of the quantizer. The digital DEM shuffler shuffles the set of partially shuffled digital data from the output of the quantizer to yield a set of shuffled digital data. The feedback digital-to-analog converter converts the set of shuffled digital data to a set of analog data to be fed back to the loop-filter.

An analog to digital converter is provided. The analog to digital converter includes: an arithmetic operator combining an analog input signal with a feedback signal; a loop filter filtering an output signal of the arithmetic operator; a quantizer quantizing an output signal of the loop filter to output a digital signal; and a feedback converting the digital signal to output a feedback signal, in which the quantizer includes: a plurality of VCOs each receiving a positive output signal and a negative output signal of the loop filter and outputting VCO signals; a plurality of samplers receiving the VCO signals output from the plurality of VCOs, respectively and outputting sampled signals; and a phase detector detecting a phase difference in the sampled signals output from the plurality of samplers, respectively, to detect a phase difference in two VCO signals output from the plurality of VCOs, respectively.

A notch filter in a sigma-delta modulator loop filter increases SNR by limiting in-band quantization noise around a frequency to which the notch filter is precisely tuned. A tuning mode controller isolates the notch filter from other loop filter stages. A bias voltage is applied to the notch filter, causing it to resonate. Tuning mode switches insert the notch filter into a frequency-locked loop (“FLL”) circuit as a variable frequency oscillator component of the FLL. An ADC operational mode input signal is applied to the FLL as a reference signal. A tuning control component of the FLL adjusts a tunable feedback element in the notch filter to drive the FLL error signal to zero in order to precisely tune the notch filter to the center frequency of the ADC input signal. Tuning inputs to the tunable feedback element are then latched prior to re-inserting the notch filter into the modulator.

The present invention provides a fractional-N frequency synthesizer comprising a divider controller comprising a multistage noise Shaping (MASH) digital delta-sigma modulator comprising L stages, wherein the jth stage is configured to receive as an input the sum of the error of the preceding stage and a high amplitude dither signal derived from the error of the kth stage, where 1≤j≤k≤L.