ADC WITH DIGITAL CALIBRATION FOR ANY ORDER NON-LINEARITY

摘要

In a pipeline ADC, a stage is selected and an order of non-linearity is selected assumed to be present in the transfer function of the interstage amplifier. The stage is controlled to operate alternately in two modes that affect the digital output signal of the last stage of the pipeline. If the non-linearity is absent from the transfer function, a difference between the output signal of the last stage in one mode and in the other mode, accumulated over a plurality of samples of the input signal to the ADC, is substantially zero. No correction of the last stage's output signal is needed. If the nonlinearity is present, the accumulated differences grow with each new sample. This is used to correct the last stage's output signal in a post-processing step with a transformation so as to bring about an overall linear transform.