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Microwatt TTL Circuits

IP.com Disclosure Number: IPCOM000080978D
Original Publication Date: 1974-Mar-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Aoki, SJ: AUTHOR [+3]

Abstract

The development of transistor-transistor-logic (TTL) circuits is directed to ensuring that high-circuit speeds are obtained at low-supply voltages. The figure shows a NAND circuit whose dissipation is extremely low at the packing density required for large-scale integration. A multiemitter transistor, whose emitters form the logic inputs IN and whose collectors are connected to the base of an output transistor T2, is used as input transistor T1. The collector of T2 forms the logic output 0 and is connected to a supply voltage V via a load element RL.

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Microwatt TTL Circuits

The development of transistor-transistor-logic (TTL) circuits is directed to ensuring that high-circuit speeds are obtained at low-supply voltages. The figure shows a NAND circuit whose dissipation is extremely low at the packing density required for large-scale integration. A multiemitter transistor, whose emitters form the logic inputs IN and whose collectors are connected to the base of an output transistor T2, is used as input transistor T1. The collector of T2 forms the logic output 0 and is connected to a supply voltage V via a load element RL.

By Schottky diodes D1 and D2 connected in parallel to their collector base paths, T1 and T2 are kept out of saturation. Resistors R1 and R2, connected in series to a supply voltage V, supply the base currents of T1 and T2. This leads to the following current requirements which are a function of the two circuit states.

When input IN is on a down level, T2 is blocked and T1 is conductive. T1 receives its base current via R1. The total current in this circuit state is thus governed by R1, branching out into the collector and the base of T1.

When inputs IN are on an up level, T1 is blocked and T2 is conductive. T2 receives its base current via series-connected resistors R1 and R2. The total current in this circuit state is thus governed by the sum of R1 and R2.

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