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Immediate-Resetting Decoder

IP.com Disclosure Number: IPCOM000041697D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Chang, WH: AUTHOR [+2]

Abstract

Firing a decoder reset pulse generator with the same signal that is used to initiate decoding, delaying the reset pulse sufficiently to ensure that the decoder has completed the decode operation, and using the delayed pulse to reset the decoder eliminates the multiple switching event problem. Fig. 1 shows a decoder from a Josephson junction memory. In a multiple switching event, a decoder gate fires two or more times, delivering a series of pulses to its load (the control line of the succeeding decoder stage or an array driver). Multiple switching is a serious problem for two reasons: First, it causes latchup of the sense line. During correct operation, the sense line driver has reset before a sense gate is fired.

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Immediate-Resetting Decoder

Firing a decoder reset pulse generator with the same signal that is used to initiate decoding, delaying the reset pulse sufficiently to ensure that the decoder has completed the decode operation, and using the delayed pulse to reset the decoder eliminates the multiple switching event problem. Fig. 1 shows a decoder from a Josephson junction memory. In a multiple switching event, a decoder gate fires two or more times, delivering a series of pulses to its load (the control line of the succeeding decoder stage or an array driver). Multiple switching is a serious problem for two reasons: First, it causes latchup of the sense line. During correct operation, the sense line driver has reset before a sense gate is fired. If a multiple switching event occurs, it may retrigger the sense line driver while a sense gate is in the voltage state. Second, multiple switching leads to failure to reset the address loop. Each time the decoder gate switches, current WIA~VWt/LA is transferred out of the address loop, where V is the voltage across the decoder gate, Wt is the time duration of the voltage, and LA is the address loop inductance. If IA falls below the floor of the reset gate, the reset gate will not fire. These two problems are eliminated by resetting the decoder immediately after it finishes decoding. Complicated timing circuitry is avoided by firing the decoder reset pulse generator with the same signal which initiates decoding, and incorpora...