Power Efficient Two Step Pipelined Analog To Digital Conversion

Hand-held devices are among the most successful consumer electronics in modern society. Behind these successful devices, lies a key analog design technique that involves high-performance analog-to-digital conversion combined with very low power consumption. This dissertation presents two different approaches to achieving high power efficiency from a two-step pipelined architecture, which is generally known as one of the most power-consuming analog-to-digital converters. In the first approach, an analog feedback loop of a residue amplifier in a two-step pipelined analog-to-digital converter is reconfigured digitally using a single comparator and an R-2R digital-to-analog converter. This comparator-based structure can reduce power consumption of a conventional two-step pipelined analog-to-digital converter which consists of an opamp-based residue amplifier followed by a second- stage analog-to-digital converter. In addition, this dissertation includes circuit design techniques that provide a digital offset correction for the comparator-based two-step structure, binary-weighted switching for an R-2R digital-to-analog converter, and reference trimming for a flash analog-to-digital converter. A 10-b prototype analog-to-digital converter achieves an FOM of 121 fJ/conversion-step under 0.7-V supply. The second approach provides a way to achieve low power consumption for a high-resolution two-step pipelined analog-to-digital converter. An opamp is designed to consume optimized static power using a quarter-scaled residue gain together with minimized loading capacitance from the proposed second stage. A 14-b prototype analog-to-digital converter achieves an FOM of 31.3 fJ/conversion-step with an ENOB of 11.4 b, which is the lowest FOM in high-resolution analog-to-digital converters having greater than an ENOB of 10 b. Finally, the potential for further power reduction in a two-step pipelined analog-to-digital converter is discussed as a topic for future research.