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High Density Diode Transistor Logic

IP.com Disclosure Number: IPCOM000089269D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Najmann, K: AUTHOR [+2]

Abstract

The integration density of a diode transistor logic gate can be considerably increased by using a lateral PNP transistor as an active element and by replacing the load resistor serving as a current sink by a transistor complementary to the lateral PNP transistor. Figs. 1, 2A and 2B are, respectively, a circuit diagram of the proposed logic gate and the plan and sectional views of its preferred integrated structure layout.

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High Density Diode Transistor Logic

The integration density of a diode transistor logic gate can be considerably increased by using a lateral PNP transistor as an active element and by replacing the load resistor serving as a current sink by a transistor complementary to the lateral PNP transistor. Figs. 1, 2A and 2B are, respectively, a circuit diagram of the proposed logic gate and the plan and sectional views of its preferred integrated structure layout.

Transistor T1 with zones P1/N(EPI)/P2 is the active element, T2 having a layer sequence of N+/P2/N(EPI) forming the current sink. Both transistors are preferably merged in an integrated form in the same isolated epitaxial layer region, as shown in Figs. 2A and 2B. Isolation is effected, for example, by a composite recessed oxide isolation (ROI) together with a P+ isolation frame.

Current sink T2 serves to control the required current and thus the necessary switching speed. For decoupling, Schottky diode (SBD) inputs with a forward voltage of about 300 - 400 mV are used. The common epitaxial layer serves as the cathode. This ensures a contact-free connection to the base of PNP transistor T1 via the subcollector.

This type of integration leads to a very small active semiconductor surface with a minimum number of contacts. Interconnection is advantageously effected in the conventional Weinberger form, and can be additionally improved by the use of a further collector P3 arranged mirror inverted to P2.

If all thre...