A calibration method for current steering digital to analog converters in continuous time multi-bit sigma delta modulators

This paper describes the general idea of a calibration method for a current steering digital-to-analog converter (DAC) in continuous time multi-bit /spl Sigma//spl Delta/ modulators. Based on the application of the so called linear regression algorithm (LRA), this method improves the linearity of the DAC's characteristics. Simulations under MATLAB on a fifth order continuous time 4bit /spl Sigma//spl Delta/ modulator for signal frequencies up to 2MHz demonstrate the effectiveness of the presented algorithm compared to the data weighted averaging (DWA) method. The algorithm's independence from the oversampling ratio makes it very attractive for modulators with low oversampling ratios.