Gilbert L Mowery

US Patent:

44171625, Nov 22, 1983

Filed:

Sep 9, 1981

Appl. No.:

6/300590

Inventors:

Jack K. Keller - Macungie PA
Gilbert L. Mowery - Allentown PA

Assignee:

Bell Telephone Laboratories, Incorporated - Murray Hill NJ

International Classification:

H03K 19003
H03K 19094
H03K 19173
H03K 1920

US Classification:

307473

Abstract:

A first MOS (metal-oxide-semiconductor) NOR-gate device feeding a second MOS NOR-gate device feeding an MOS output load device is arranged to yield a three output level buffer circuit, that is, whose output to a common data bus line can be "high" ("1"), "low" ("0"), or of very high impedance ("floating"). Each NOR-gate contains a low. beta. ("load") depletion mode type of MOS transistor and a high. beta. ("driver") enhancement mode type of MOS; the output load device contains an output driver enhancement mode type of MOS transistor and an output load MOS transistor having a threshold intermediate that of the depletion mode and enhancement mode type of MOS transistor. In this manner, only a single voltage source V. sub. DD, or typically about +5 volts in N-MOS integrated circuit technology is required to power the buffer circuit completely.