High speed multibit oversampling noise shaping ADCs

For very high speed operation, single bit oversamplers have disadvantages when compared to multibit devices. However, achieving the linearity in the feedback DAC has hitherto prevented the widespread adoption of the multibit approach. A new technique is demonstrated that achieves arbitrary linearity, and low noise, from the feedback DAC without the use of calibration. The application to monolithic ADCs, with dynamic ranges in excess of 100 dB at signal bandwidths in excess of 10 MHz, is discussed