A negatively biased substrate has several advantages over a grounded substrate in CMOS
technology. The on-chip generation of this negative substrate bias has made chips easier
to use when only a single supply is preferred. This project demonstrates two types of
charge pump circuits used to generate negative voltages not only for biasing the substrate,
but in a broader sense also for other purposes in CMOS technology. One other possible
use is in conjunction with 'Guard Ring Diodes for Suppressing the Substrate Noise in
Mixed-Mode CMOS Circuits'. This work proposes a reasonable approach to generate the
forward biasing current for the guard ring diode whose depletion capacitance and the
substrate lead inductance form a resonant circuit to provide very low substrate-to-ground
impedance at specific frequencies. Given this emphasis on generating a reasonably
predictable current source, the generated negative voltages are regulated using a feedback
loop. The amplitude of this negative voltage can be determined exclusively by transistor
sizes.
Simulation results support the theoretical analysis in that accurate negative voltages and
current sources can be generated on-chip, although there are some limitations. / Graduation date: 1996
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34653 |
| Date | 27 November 1995 |
| Creators | Zhang, Jing, 1962- |
| Contributors | Forbes, Leonard |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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