Analysis and Design of High-Speed ADCs

High-speed analog-to-digital converters (ADCs) are at the heart of many applications such as digital communication, video, and instrumentation. However, the power efficiency of ADCs tends to degrade as higher speeds and/or resolutions are sought. In this research, we introduce a low-power high-speed pipelined ADCarchitecture that employs a precharged resistor-ladder digital-to-analog converter (RDAC) and a multi-bit front end with a low-gain op amp. Avoiding the need for op amp nonlinearity calibration, the ADC only computes the gain errors and corrects them in the digital domain. In addition, RDAC simplifies the calibrationlogic and enables high-speed gain error calibration, thus correcting for the incomplete settling of the MDACs. Using simple differential pairs with gains of about 5 as op amps and realized in 65-nm CMOS technology, the 10-bit ADC consumes 36 mW at a sampling rate of 1 GHz and exhibits an FOM of 70 fJ/conv.-step.A critical issue in the design of high-speed ADCs relates to errors that result from comparator metastability. Studied for only flash architectures, this phenomenon assumes new dimensions in pipelined converters, creating far more complex error mechanisms. In this dissertation, we present a comprehensive anal-ysis of comparator metastability effects in pipelined ADCs and develop a method to precisely predict the error behavior for a given input signal p.d.f