US 7,679,539 B2 · Randomized thermometer-coding digital-to-analog converter and method therefor

Abstract

A randomized thermometer-coding digital-to-analog converter (DAC) for the reduction of harmonic distortion due to non-ideal circuit mismatch is presented. The present invention introduces a new dynamic element matching technique that contains three properties of randomization, consecutive selection and less element switching activity to achieve good spurious-free dynamic range and small maximum output error. The topology uses a bank of 1-bit DAC elements, whose outputs are summed to produce a multi-level analog output. The binary digital input is encoded to be thermometer code. During a randomization period, the thermometer code is barrel-shifted to a specific starting position where the position is generated randomly. Thus, the DAC noise is randomized with less element switching activity and consecutive selection.

Claims12

Dependent claims

A randomized thermometer-coding digital-to-analog converter for converting an N-level thermometer coded digital input to an analog output, comprising:

an encoder which barrel shifts said N-level thermometer coded digital input to a specific starting position;
a random number generator which generates a random number and sends said random number to said encoder to decide said specific starting position;
a randomization period generator which produces a randomization period and sends said randomization period to said random number generator, wherein said randomization period controls said encoder to shift said N-level thermometer coded digital input to said specific starting position during said randomization period;
a plurality of digital-to-analog converter elements which receive the outputs of said encoder to generate respective analog outputs;
and
an analog output summing node which receives and sums said respective analog outputs to generate said analog output.

3 more elements

Dependencies are inferred from the claim text.

Randomized thermometer-coding digital-to-analog converter and method therefor

Life of this patent

Randomized thermometer-coding digital-to-analog converter and method therefor

Life of this patent

Abstract

Claims12