A 13-B 10-MSAMPLE S ADC DIGITALLY CALIBRATED WITH OVERSAMPLING DELTA-SIGMA CONVERTER/

Two key techniques necessary to digitally calibrate multistep or pipel ined converters are demonstrated in a differential 5-V, 13-b, 10-Msamp le/s analog-to-digital converter (ADC), One technique, called code-err or calibration, is to linearize the transfer characteristic of digital -to-analog converters (DAC's) while the other, called gain-error prora tion, is to evenly distribute interstage gain errors over the full con version range, The core of the former technique is an oversampling del ta-sigma ratio calibrator working synchronously with the converter, Th is digital calibration process constantly tracks and updates the code errors without interfering with the normal operation, The prototype co nverter fabricated using a 1.4-mu m BiCMOS process consumes 360 mW wit h a 5-V single supply and exhibits a signal-to-noise ratio of 71 dB an d a maximum end-point integral nonlinearity of 1.8 LSB at a 13-b level , The proposed techniques can be incorporated into general multistep o r pipelined ADC's without sacrificing the conversion speed.