Design Of Digital Calibration Methods For Pipelined Analog-to-Digital Converters

This paper mainly presents the realization of digital backgroundcalibration for high-resolution，high speed pipelined ADCs.First of all, this paper introduces the principle and structure ofpipelined ADCs. Then in order to generate the reference voltage for ADC,a novel bandgap reference with curvature correction is proposed. Thisbandgap reference introduces compensating voltage to eliminatesecond-order effect. The simulation result shows that temperaturecoefficient is within6ppm/oC from-40oC to135oC.Next this paper introduces the error sources that needed to becalibrated in pipelined ADCs. To correct these error sources, radix-baseddigital calibration method is introduced. Although this method has somedisadvantages, it can improve the SNDR greatly and achieve a goodENOB.Last but not least, this paper proposes a digital calibration techniqueusing signal-dependent PN(Pseudo-random sequence) dithering. Thismethod can realize background calibration for pipelined ADCs.Pseudo-random sequence features are used to complete statistic analysis.The principle of injecting PN dithering and implementation of circuit ismentioned in detail. The simulation results show that this method canrealize synchronous calibration. Compared to several methods mentionedin references, this method improves the SNDR and reduces calibrationtime. Extra hardwares are affordable and digital controllers are notcomplex. Thus this paper achieves a better calibration method.