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Storage Device Signal Shaping

IP.com Disclosure Number: IPCOM000092464D
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Przekurat, KD: AUTHOR [+2]

Abstract

In some magnetic memories, the stored logic value is represented by the polarity of the signal that is developed on a sense line during a read operation. For example, in some thin-film memories, binary values are stored in opposite directions along an easy axis of magnetization. The elements are read by switching the magnetization into an orthogonal hard axis. The polarity of the voltage associated with this change of magnetization signifies the previous storage direction of the element. In memories of this type, noise that is produced on the sense line can be made to enhance the signals produced by the storage elements. This noise is capacitively coupled from the lines that are energized to switch the storage elements for reading. The noise tends to add to positive signals that represent a 1.

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Storage Device Signal Shaping

In some magnetic memories, the stored logic value is represented by the polarity of the signal that is developed on a sense line during a read operation. For example, in some thin-film memories, binary values are stored in opposite directions along an easy axis of magnetization. The elements are read by switching the magnetization into an orthogonal hard axis. The polarity of the voltage associated with this change of magnetization signifies the previous storage direction of the element. In memories of this type, noise that is produced on the sense line can be made to enhance the signals produced by the storage elements. This noise is capacitively coupled from the lines that are energized to switch the storage elements for reading. The noise tends to add to positive signals that represent a 1. It subtracts from the negative signals that represent a
0. Thus a signal representing a 0 is made to have approximately zero voltage level. A signal representing a 1 is given about twice the amplitude produced by the storage device. This combination of the signal and noise is easier to detect than the signal alone. The waveforms illustrate an improved operation in such a storage device. The wider lines represent the improved memory and the narrower lines represent a conventional memory.

The read noise for a magnetic film is a function of several factors, including the rate of change of the read current. The upper left-hand waveform shows the conventional read current which rises rapidly to its peak amplitude. The corresponding noise shown in the next waveform has steep leading and trailing edges associated with the fairly abrupt transitions in the rate of rise of the conventional read current. As the next waveform shows, the storage element output signal is delayed...