Digital Acceleration of Correlation-Based Digital Background Calibration in Pipelined ADCs

We present here a general digital method to accelerate correlation-based digital background calibration in pipelined ADCs. The central task in correlation-based background calibration is the extraction of component mismatch information from correlated data sequences. Using an explicit frequency domain analysis, we treat the extraction process as discrete-time low pass filtering. We then show that a higher-order, variablebandwidth filter, while adding minimal digital cost, rapidly extracts mismatch information, making calibration 18 times faster in simulation than the 1st-order, fixed bandwidth filter. The latter filter functions essentially the same as the currently widely used extraction algorithm, such as the sequential iterative algorithm or the signal averager.

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