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Browse Prior Art Database

Off-Chip Drivers Using Short Channel CMOS Devices

IP.com Disclosure Number: IPCOM000059674D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Swietek, D: AUTHOR

Abstract

Short Channel CMOS (complementary metal oxide semiconductor) devices make possible the design of off-chip drivers that will meet bipolar performance levels. This article describes two high performance off- chip driver circuits, a three-state push-pull driver and an open-drain driver together with corresponding layouts and controls, that will provide required small voltage swing levels and rise/fall times equal to or better than bipolar drivers. Referring to the drawing, the three-state logical control is provided by devices Q5 and Q6. These allow both of the output devices Q19 and Q20 to be turned off.

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Off-Chip Drivers Using Short Channel CMOS Devices

Short Channel CMOS (complementary metal oxide semiconductor) devices make possible the design of off-chip drivers that will meet bipolar performance levels. This article describes two high performance off- chip driver circuits, a three-state push-pull driver and an open-drain driver together with corresponding layouts and controls, that will provide required small voltage swing levels and rise/fall times equal to or better than bipolar drivers. Referring to the drawing, the three-state logical control is provided by devices Q5 and Q6. These allow both of the output devices Q19 and Q20 to be turned off. Device Q18 would attach to a control bus on the chip in such a manner that, throughout wafer test while all drivers are in a high-impedance state, they would be selectively activated by the dI/dT chip bus as required due to the lack of simultaneous switching control during the test mode. These two logical controls are necessary functions for VLSI (very large-scale integrated) off-chip drivers. Because it is desirable to maximize the number of drivers that can be switched, a method to control dV/dT is also provided. Devices Q12, Q13, Q16 and C2 (for an open-drain driver) and Q7, Q8, Q12, Q13 and Q16, C1 and C2 (for a three-state driver) perform this function. The device sizes are tailored such that the gate nodes of the output devices can be switched down very quickly but, in the up-going transition, very slowly. Q12...