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Ladder Network for Counting

IP.com Disclosure Number: IPCOM000082055D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Matisoo, J: AUTHOR

Abstract

In some logic circuits, it is necessary to count the number of operations performed to decide whether an operation should continue or stop. Various means can be used for counting such as an accumulator to which 1 is added, flip-flop shift registers and the like. These approaches, however, are rather elaborate.

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Ladder Network for Counting

In some logic circuits, it is necessary to count the number of operations performed to decide whether an operation should continue or stop. Various means can be used for counting such as an accumulator to which 1 is added, flip-flop shift registers and the like. These approaches, however, are rather elaborate.

A simple network which counts inputs by shifting current down a ladder is described herein. In Fig. 1, the arrival of current at some point signals the count and an operation based on that count can be terminated. Fig. 1 illustrates the idea for a count to three.

In Fig. 1, a superconductive ladder network is shown which contains Josephson junction gates 1-3 and diodes 4,5. The circuit assumes that the line lengths and widths utilized are such that each line section has the same inductance. Diodes 4-5 are designed so that they always remain superconducting in the forward direction. Fig. 2 shows such a characteristic. A common control line 6 runs over the Josephson junctions 1-3. The current in loops 7,8,9 may be sensed by sense gates 10,11,12 which are Josephson tunneling devices.

For purposes of illustration, it is assumed that the gain curve for each of the gates 1-3 is as shown in Fig. 3. Further, it is assumed that Ig = 56i.

Before any input pulse, Ic, is applied to control line 6, the operating points of gates 1-3 are shown by the open circles in Fig. 3. Application of a pulse Ic to control line 6 of a magnitude equal to app...