Browse Prior Art Database

C2G Emitter Dot

IP.com Disclosure Number: IPCOM000042525D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Dorler, JA: AUTHOR [+2]

Abstract

The standard capacitively coupled gate (C2G), shown in Fig. 1, comprising a pull-up transistor T1 and pull-down transistor T2 is known for its good delay characteristic, for example, a delay of 400 ps at 1 mw power level. A disadvantage of this circuit, however, is that it is restricted to achieving the logic NOR function since if the outputs of two such C2G circuits are dotted (which is desirable in gate array applications) they suffer from contention manifested by excessive current flow due to the simultaneous turning on of the pull-up and pull-down transistors. The above shortcoming of the standard C2G circuit can be alleviated by the novel dottable C2G circuit configuration illustrated in Fig. 2. The dottable C2G is achieved by removing the active pull- down transistor T2 of Fig.

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C2G Emitter Dot

The standard capacitively coupled gate (C2G), shown in Fig. 1, comprising a pull-up transistor T1 and pull-down transistor T2 is known for its good delay characteristic, for example, a delay of 400 ps at 1 mw power level. A disadvantage of this circuit, however, is that it is restricted to achieving the logic NOR function since if the outputs of two such C2G circuits are dotted (which is desirable in gate array applications) they suffer from contention manifested by excessive current flow due to the simultaneous turning on of the pull-up and pull- down transistors. The above shortcoming of the standard C2G circuit can be alleviated by the novel dottable C2G circuit configuration illustrated in Fig. 2. The dottable C2G is achieved by removing the active pull- down transistor T2 of Fig. 1 and substituting in its place a current source I which may be, for example, a resistor. Since the pull-down transistor is eliminated, the circuit is essentially an emitter follower whose output can be dotted easily without the push/pull contention problem.

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