High Speed Fast-Settling OTA

Designed by
Erik McCarthy

Dept.of Elec. and Comp. Engineering
University of Maine, Orono.

Computer chip

This ECE547 VLSI Design project consists of an Operational Transconductance Amplifier (OTA) to be used in the gainstage of a pipelined A/D Converter. The OTA is designed to charge 500fF switched capacitors with a settling time less than 5ns. The design is based on a telescopic architecture for optimal speed. There are nine fully differential OTA’s and a 250MHz ring oscillator on the layout.

MOSIS implements the device in AMI’s C5N process technology. The 0.5 micron minimum gate length is physically designed on a 0.15 micron grid. This constrains the gate length to a minimum of 0.6 microns. The die size is 1.5 X 1.5 mm and is packaged in a 40 pin DIP.

The project report (PDF) contains a project description with design and layout considerations and test results.

May 2003