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Noise and Signal Shaping in a Magnetic Thin Film Memory

IP.com Disclosure Number: IPCOM000092468D
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Caricari, CA: AUTHOR [+2]

Abstract

The waveforms in the drawing show an improved memory operation. The waveforms of group 1 show a conventional word current pulse that is used to read data from a memory. In response to such pulse, magnetic storage elements of the memory go through a flux change that produces a read signal voltage that signifies the data stored in the element. The conductor that carries the word current is capacitively coupled to a conductor that picks up the read signal. This capacitive coupling produces noise on the sense line that is proportional to the rate of change of the word current. For the somewhat idealized waveforms of group 1, the noise is approximately rectangular. This noise occurs at about the time of the signal produced by a storage element. In some memories this effect can be used to enhance the signal output.

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Noise and Signal Shaping in a Magnetic Thin Film Memory

The waveforms in the drawing show an improved memory operation. The waveforms of group 1 show a conventional word current pulse that is used to read data from a memory. In response to such pulse, magnetic storage elements of the memory go through a flux change that produces a read signal voltage that signifies the data stored in the element. The conductor that carries the word current is capacitively coupled to a conductor that picks up the read signal.

This capacitive coupling produces noise on the sense line that is proportional to the rate of change of the word current. For the somewhat idealized waveforms of group 1, the noise is approximately rectangular. This noise occurs at about the time of the signal produced by a storage element. In some memories this effect can be used to enhance the signal output.

Some thin-film memories produce positive polarity signals to represent 1's and produce negative polarity signals to represent 0's. The capacitively coupled noise tends to cancel a negative signal and to approximately double the amplitude of a positive signal. As a result of this combination of voltages, such a memory produces approximately zero voltage level for a 0 and a positive voltage level for a 1. Such a composite signal is simpler to detect than the initial signal in which a polarity represents the data.

The waveforms of group 2 show how this effect can be enhanced. The noise signal is shaped to...