Nxp B.v.

Chenming Zhang

Lucien Johannes Breems

Muhammed Bolatkale

Marcello Ganzerli

Pierluigi Cenci

Shagun Bajoria

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.

System and method of replicating and cancelling chopping folding error in delta-sigma modulators

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 2filtered 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.

Sigma delta modulator and method therefor

The present disclosure relates generally to techniques for continuous-time sigma-delta analog-to-digital converter (ADC). The continuous-time sigma-delta ADC may include a feed-forward capacitor in parallel with a current-steering excess loop delay (ELD) digital-to-analog converter (DAC), and by creating a zero in a transfer function of a Gm cell, both an ELD feedback loop settling and a main feedback loop may be recovered. As a result, the performance and stability of the continuous-time sigma-delta ADC can be achieved. Additionally, a summation node in the continuous-time sigma-delta ADC may offer flexibility in the architecture design of the continuous-time sigma-delta ADC.

Techniques for high-speed excess loop delay compensation in sigma-delta analog-to-digital converters

The present disclosure relates generally to techniques for linearizing a digital-to-analog converter (DAC) in a continuous-time sigma-delta ADC. A sigma-delta ADC may be configured with a multibit quantizer for various applications. These applications may require wide-bandwidth high-resolution high-linearity power-efficient ADCs. In some embodiments, a mismatch of a multibit DAC might result in a bottleneck for achieving high linearity performance. Some linearization techniques may achieve high linearity performance. However, for a high-speed sigma-delta ADC, the DAC is configured to be part of a feedback loop. Existing linearization techniques often increase the delay in the feedback loop, which is not desired. Various aspects of the present disclosure provide improvement to linearization techniques by changing the references of the multibit quantizer. As a result, this reduces delay in the feedback loop of the sigma-delta modulator, which is beneficial for high-speed sigma-delta ADCs.

Techniques for linearizing digital-to-analog converters in sigma-delta analog-to-digital converters

A N-bit continuous-time sigma-delta modulator, SDM, () includes an input configured to receive an input analog signal (); a first summing junction () configured to subtract a feedback analog signal () from the input analog signal (); a loop filter () configured to filter an output signal from the first summing junction (): an N-bit analog-to-digital converter, ADC, comprising at least one 1-bit ADC configured to convert the filtered analog output signal () to a digital output signal () where each 1-bit ADC comprises at least one pair of comparator latches (); and a feedback path () for routing the digital output signal to the first summing junction (). The feedback path () includes a plurality of digital-to-analog converters, DACs, configured to convert the digital output signal () to an analog form. The ADC comprises or is operably coupled to, a calibration circuit () coupled to an input and an output of the at least one pair of comparator latches () and configured to apply respective calibration signals to individual comparator latches of the at least one pair of comparator latches () in a time-Interleaved manner, and calibrate a comparator error of the comparator latches in response to a latched output of the respective calibration signals.

Sigma delta modulator, integrated circuit and method therefor

A method includes using a first feedback loop to compensate for a first excess loop delay (ELD) associated with a first quantizer and a first DAC of the first feedback loop. The first quantizer provides a first quantizer output to a second feedback loop. A second feedback loop compensates for a second ELD associated a second quantizer and a second DAC of the second feedback loop. The second quantizer reduces a metastability error associated with the first quantizer output.

Metastability shaping technique for continuous-time sigma-delta analog-to-digital converters

A multi-bit continuous-time sigma-delta modulator, SDM, includes an input configured to receive an input analog signal; a first summing junction configured to subtract a feedback analog signal from the input analog signal; a loop filter configured to filter an output signal from the first summing junction: an analog-to-digital converter, ADC, configured to convert the filtered analog output signal to a digital output signal; and a feedback path for routing the digital output signal to the first summing junction. The feedback path includes a plurality of digital-to-analog converters, DACs, configured to convert the digital output signal to an analog form. The ADC includes multiple per-bit parallel loops, each loop configured to provide a per-bit current summation of the filtered analog output signal such that an output of the multiple per-bit parallel loops is a multi-bit quantization digital output signal.

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Eindhoven, Netherlands

Chenming Zhang