Automatic Synthesis of CMOS Digital/Analog Converters by Robert McKinstry Robinson Neff Doctor of Philosophy in Engineering -- Electrical Engineering and Computer Sciences University of California at Berkeley Professor Paul R. Gray, Chair Synthesis of analog functional blocks in integrated circuits offers promise for improved designer productivity. By developing module generators for commonly used analog circuit elements, a synthesis methodology may be matched to a particular application, with approaches and algorithms determined by the particular needs of target circuit type. An analog circuit designer should be able to input design specifications and underlying technology information, and a synthesis methodology should determine circuit parameter values and dimensions, creating the required mask layouts. Slow, tedious design and redesign methods should be replaced by one in which the computer finds minimum cost designs which meet performance requirements. This work implements synthesis methods for a widely used analog block, the digital/analog converter (DAC).

Abstract — A 14-bit digital-to-analog converter based on a fourth-order multibit sigma–delta modulator is described. The digital modulator is pipelined to minimize both its power dissipation and design complexity. The 6-bit output of this modulator is converted to analog using 64 current-steering cells that are continuously calibrated to a reference current. This converter achieves 85-dB dynamic range at 5-MHz signal bandwidth, with an oversampling ratio of 12. The chip was fabricated in a 0.5-"m CMOS technology and operates from a single 2.5-V supply. Index Terms — Current calibration, digital-to-analog conversion, mixed analog–digital integrated circuits, multibit modulators, pipelined adders, sigma–delta modulation. I.