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Metal Oxide Silicon Integrated Circuit Substrate Bias Circuit

IP.com Disclosure Number: IPCOM000059726D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Bednar, TR: AUTHOR [+3]

Abstract

Prevention of minority carriers (usually electrons) from being injected into the substrate is featured in this metal oxide silicon (MOS) substrate bias circuit. MOS on-chip substrate voltage generators have the following basic elements, as shown in the figure: 1) A ring oscillator to generate AC signals from a power supply. 2) A coupling capacitor "CC" to remove any DC offset voltage. 3) A rectifier 10 to convert the AC signal to a negative volt age. 4) An optional regulator (not shown) to control the magnitude of the voltage generated. The ring oscillator signal A is coupled through coupling capacitor CC to drive the field-effect transistor (FET) 10. Negative excursions of the drive pulse E cause transistor 10 to cut-off and rectify the square-wave pulses which bias the drain of transistor 11.

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Metal Oxide Silicon Integrated Circuit Substrate Bias Circuit

Prevention of minority carriers (usually electrons) from being injected into the substrate is featured in this metal oxide silicon (MOS) substrate bias circuit. MOS on-chip substrate voltage generators have the following basic elements, as shown in the figure:
1) A ring oscillator to generate AC signals from a power supply. 2)

A coupling capacitor "CC" to remove any DC offset voltage. 3) A rectifier 10 to convert the AC signal to a negative volt age. 4)

An optional regulator (not shown) to control the magnitude of the voltage generated. The ring oscillator signal A is coupled through coupling capacitor CC to drive the field-effect transistor (FET) 10. Negative excursions of the drive pulse E cause transistor 10 to cut-off and rectify the square-wave pulses which bias the drain of transistor 11. An additional ring oscillator stage 12 is used to generate a train of square-wave pulses B which are 180 degrees out of phase with pulse train A. The B pulses are differentiated by the RC network and applied to the gate of transistor 11. This transistor is used in place of a diode because a diode can inject minority carriers into the substrate. The rectified A pulses bias transistor 11, and the differential pulses applied to the gate cause current pulses I to flow and bias the substrate negative. By replacing an FET diode with an FET 11 coupled to a driving signal (derived from the ring oscillator) by means of a...