An analog-to-digital conversion system includes two quantizers having a least significant bit arranged in a parallel pair. An input circuit coupled to the quantizers provides an analog input signal to the quantizers. A dither generator coupled to the quantizers provides an analog differential dither signal for perturbing quantization of the analog input signal. A combiner coupled to the quantizers adds respective outputs of the quantizers to obtain a linearized digital representation of the analog input signal.

An analog-to-digital conversion system includes two quantizers having a least significant bit arranged in a parallel pair. An input circuit coupled to the quantizers provides an analog input signal to the quantizers. A dither generator coupled to the quantizers provides an analog differential dither signal for perturbing quantization of the analog input signal. A combiner coupled to the quantizers adds respective outputs of the quantizers to obtain a linearized digital representation of the analog input signal.

The disclosed invention is a sigma-delta modulator based ADC and a dithering method thereof. An analog dither circuit of an input stage in a quantizer, which is configured to perform dithering, receives an integrator output signal from an output of an integrator and a plurality of digital dither signals from digital dither generator, and employs these signals to produce multi-level analog dither signals via the operation of a plurality of transistors as switches coupled with a plurality of resistors coupled in series. The multi-level analog dither signals can prevent, reduce, or eliminate limit cycle in the sigma-delta modulator based ADC. Furthermore, disclosed invention does not require fixed load capacitance, resulting in no extra power consumption and solve the problem as the kickback noise variation.

A method for reducing the jitter introduced into a digital signal by a non-linear processing element involves applying an input word representing the digital signal to a first signal path comprising a first non-linear processing element, and a complementary version of the input word to a second signal path comprising a second non-linear processing element. A common mode dither signal is injected into each signal path upstream of the non-linear processing elements. The outputs of the non-linear processing elements are combined to produce a common output with the common mode dither signal removed.

A digital-to-analog converter includes an adder having a plurality of inputs and an output coupled to the output of the converter. The converter further includes a plurality of digital-to-analog (DAC) elements, each DAC element has an output coupled to an input of the adder, and each DAC element has a DAC element input. A plurality of comparators have outputs coupled to a DAC element input. A first input of each comparator is coupled to the input of the converter. A second input of each comparator is selectively coupled to one of a predetermined voltage and a pseudo-random bit sequence (PRBS[n]).

A delta-sigma modulator (10) comprises a modulator loop (11) and a code generator (12). The modulator loop (11) comprises a loop filter (18). The code generator (12) is configured to generate a generator signal (BS) that is realized as an extended Barker code. The code generator (12) comprises a generator output (23) that is coupled to the loop filter (18).

A method for reducing the jitter introduced into a digital signal by a non-linear processing element involves applying an input word representing the digital signal to a first signal path comprising a first non-linear processing element, and a complementary version of the input word to a second signal path comprising a second non-linear processing element. A common mode dither signal is injected into each signal path upstream of the non-linear processing elements. The outputs of the non-linear processing elements are combined to produce a common output with the common mode dither signal removed.

A delta-sigma modulator (10) comprises a modulator loop (11) and a code generator (12). The modulator loop (11) comprises a loop filter (18). The code generator (12) is configured to generate a generator signal (BS) that is realized as an extended Barker code. The code generator (12) comprises a generator output (23) that is coupled to the loop filter (18).

A measuring circuit measures an interleaving (IL) spur of at least one time-interleaved digital-to-analog converter (DAC) included in a delta-sigma (DS) analog-to-digital converter (ADC). The measuring circuit includes a dither tone generator circuit and a digital signal processing circuit. The dither tone generator circuit generates a dither tone with a pre-defined tone frequency, and injects the dither tone to the DS ADC. The digital signal processing circuit processes a digital output of the DS ADC with the dither tone injected, to generate a measurement result of the IL spur that is induced by the at least one time-interleaved DAC due to the injected dither tone.

The disclosed invention is a sigma-delta modulator based ADC and a dithering method thereof. An analog dither circuit of an input stage in a quantizer, which is configured to perform dithering, receives an integrator output signal from an output of an integrator and a plurality of digital dither signals from digital dither generator, and employs these signals to produce multi-level analog dither signals via the operation of a plurality of transistors as switches coupled with a plurality of resistors coupled in series. The multi-level analog dither signals can prevent, reduce, or eliminate limit cycle in the sigma-delta modulator based ADC. Furthermore, disclosed invention does not require fixed load capacitance, resulting in no extra power consumption and solve the problem as the kickback noise variation.