Multi-bit sigma-delta modulator employing dynamic element matching using adaptively randomized data-weighted averaging

A sigma-delta modulator, comprising:

• a summer coupled to receive an analog input signal;
• a analog loop filter having a noise shaping function coupled to receive the output of the summer;
• an analog-to-digital converter coupled to receive the filtered signal to convert the signal to a digital output signal;
• and
• a feedback path from the analog-to-digital converter to the summer, the feedback path comprising at least one dynamic element matching algorithm logic block coupled to a digital-to-analog converter having a plurality of unit elements to minimize the mismatch error associated with the plurality of unit elements, wherein the dynamic element matching algorithm logic block alternately generates an incremental shift signal and a random shift signal at a predetermined time interval for shifting the digital feedback signal by a random amount depending upon the amplitude and frequency of the analog input signal to provide a randomized rotated output.

A dynamic element matching circuit, comprising:

• a random number generator to generate a first and a second random number;
• a latch coupled to receive an analog input signal;
• an encoder coupled to the latch to provide an encoded digital signal;
• an amplitude detector coupled to receive the input signal to detect the amplitude of the input signal;
• at least one storage device having a table of probability variables, the storage device coupled to the amplitude detector and coupled to receive a system clock;
• at least one comparator coupled to receive one of the probability variables from the storage device and the first random number to produce a control signal;
• at least one first multiplexer having a first and second input, a control input, and an output, the first and second inputs coupled to receive the encoded digital signal and the second random number, the control input coupled to receive the control signal such that when the first random number is less than the probability variable, the second random number is provided at the output of the first multiplexer and when the first random number is greater than or equal to the probability variable, the encoded digital signal is provided at the output of the first multiplexer;
• at least one summer having a first and second input and an output to provide a shift signal, the first input coupled to the output of the first multiplexer;
• at least one delay coupled between the output of the summer and the second input of the summer to provide feedback;
• a decoder coupled to the at least one summer to decode the shift signal;
• and
• a barrel shifter comprises,
• a plurality of shifting units forming a shifting column, the shifting column configured to receive the digital feedback signal,
• a first input for each of the plurality of shifting units, the first input receiving a single bit of the digital feedback signal,
• a second input for each of the plurality of shifting units, the second input connected to the first input of another one of the plurality of shifting units, and
• a select line coupled to the decoder to apply the shift signal to the plurality of shifting units effectuating a shift of the digital feedback signal received by the first input to produce a randomized rotated output.

A sigma-delta modulator, comprising:

• a summer coupled to receive an analog input signal;
• a analog loop filter having a noise shaping function coupled to receive the output of the summer;
• an analog-to-digital converter coupled to receive the filtered signal to convert the signal to a digital output signal;
• and
• a feedback path from the analog-to-digital converter to the summer, the feedback path comprising at least one dynamic element matching algorithm logic block coupled to a digital-to-analog converter having a plurality of unit elements to minimize the mismatch error associated with the plurality of unit elements to generate a digital feedback signal, wherein the dynamic element matching algorithm logic block alternately generates an incremental shift signal and a random shift signal at a random time interval for shifting the digital feedback signal by a random amount depending upon a probability variable to provide a randomized rotated output.

A method of distributing mismatched error associated with a plurality of data converter elements, comprising the steps of:

• a. filtering an analog input signal using a filter configured to perform a noise shaping function on the analog input signal and to generate a processed signal;
• b. converting the processed signal into a digital output signal using an analog-to-digital converter;
• c. feeding back the digital output signal to a dynamic element matching logic block to alternately shift the digital feedback signal incrementally and randomly at a predetermined time interval by a random amount depending upon the amplitude and frequency of the analog input signal to generate a randomized rotated output;
• e. converting the randomized rotated output into an analog feedback signal;
• f. summing the analog feedback signal with the input analog signal to provide a modified analog input signal to minimize the error associated with the plurality of data converter elements;
• and
• g. repeating steps a through f.

A method of distributing mismatched error associated with a plurality of data converter elements, comprising the steps of:

• a. filtering an analog input signal using a filter configured to perform a noise shaping function on the analog input signal and to generate a processed signal;
• b. converting the processed signal into a digital output signal using an analog-to-digital converter;
• c. feeding back the digital output signal to a dynamic element matching logic block to alternately shift the digital feedback signal incrementally and randomly at a random time interval by a random amount depending upon a probability variable to generate a randomized rotated output;
• e. converting the randomized rotated output into an analog feedback signal;
• f. summing the analog feedback signal with the input analog signal to provide a modified analog input signal to minimize the error associated with the plurality of data converter elements;
• g. repeating steps a through f.