Getting a Grip on the Regenerative Comparator

Wednesday, March 21, 2018
12:00 PM to 1:00 PM
EER 1.518
Free and open to the public

The regenerative comparator is at the heart of A/D converters and digital communication receivers. It senses the memory cell in SRAM and DRAM.

Since the circuit is unstable and always operates with large signal swings that drive transistors to the extreme, so far there is no well-known method for a quantitative analysis of the circuit.

I will show that by exploiting circuit symmetry, its dynamics can be fully visualized in the phase plane defined by the circuit’s two orthogonal modes. From this follow decompositions into simple equivalent circuits for each mode, and they show how static and dynamic offsets arise from transistor and load unbalance. At low supply voltages, the offset and noise in the comparator can become the bottleneck to system performance.

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Asad Abidi


Asad Abidi received the BSc degree in Electrical Engineering from Imperial College, London in 1976, and the PhD from the University of California, Berkeley in 1982. He worked at Bell Laboratories, Murray Hill until 1985, and then joined the faculty of the University of California, Los Angeles where he is Distinguished Chancellor’s Professor of Electrical Engineering. With his students he has developed many of the radio circuits and architectures that enable today’s mobile devices.

Among other awards, Professor Abidi has received the 2008 IEEE Donald O. Pederson Award in Solid-State Circuits and the 2012 Best Paper Award from the IEEE Journal of Solid-State Circuits. The University of California, Berkeley’s Department of EECS recognized him as a Distinguished Alumnus in 2015. He was elected Fellow of IEEE in 1996, Member of the US National Academy of Engineering, and Fellow of TWAS, the world academy of sciences.