A robust background calibration technique for switched-capacitor pipelined ADCs

Abstract

This work presents a robust background calibration scheme for switched-capacitor (SC) pipelined analog-to-digital converters. A SC multiplying digital-to-analog converter (MDAC) is usually linearized by high-gain capacitive feedback. Its conversion gain can be measured by splitting the input sampling capacitor and injecting a random sequence into the signal path. The magnitude of the random sequence can be extracted later in the digital domain. The use of input-dependent generation of the random sequence can eliminate the extra signal range requirement and also save calibration time. Furthermore, the use of random choppers to scramble signal can ensure that all necessary calibration data can be collected within a given time regardless of input conditions, resulting in a more robust ADC.