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AC Powered Latch

IP.com Disclosure Number: IPCOM000052093D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Davidson, A: AUTHOR

Abstract

This article relates to a latch which is powered with bipolar AC currents. The circuits combine a Josephson latching-logic circuit with a temporary information storage ring. The object is to store information in the latching-logic circuit during the powered portion of a logic cycle, and in the storage ring during the part of the cycle in which the latching-logic circuit resets and the power supply changes polarity. A working circuit must contain the means for transferring information between two storage elements and means for changing the stored information.

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AC Powered Latch

This article relates to a latch which is powered with bipolar AC currents. The circuits combine a Josephson latching-logic circuit with a temporary information storage ring. The object is to store information in the latching-logic circuit during the powered portion of a logic cycle, and in the storage ring during the part of the cycle in which the latching-logic circuit resets and the power supply changes polarity. A working circuit must contain the means for transferring information between two storage elements and means for changing the stored information.

One such circuit is shown in Fig. 1. In Fig. 1, flip-flop 1 includes a loop formed by elements ABDT. ABT is the storage ring, and D is a latching-logic OR gate. The operation is as follows: Starting from the initial application of AC power, gate current rises in actuable gates A and D causing a complement signal to appear at output C. Flip-flop 1 is therefore initially in the "zero" or reset state.

If during this logic cycle a signal is applied to device D via control line S (Set), device D and then device A (via feedback path 2 switch, transferring current into the temporary storage loop formed by elements ABT. Resistor r disposed in series in this loop is chosen so that device A resets as soon as control current is removed from feedback path 2 at the end of the cycle. When device A resets, a decaying current is stored in elements B, L, and T. By choosing L/r correctly, this decaying current can be made to persist throughout the reset portion of the cycle and thereby retain the information that flip-flop 1 is in the "one" or set state. Then, as the applied AC power comes up in the next cycle with opposite polarity, t...