Browse Prior Art Database

Drive System with Noise Cancellation

IP.com Disclosure Number: IPCOM000095938D
Original Publication Date: 1964-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Grubb, HR: AUTHOR [+3]

Abstract

In this drive system for a capacitor read-only storage, a controlled out-of-phase signal is generated to compensate for noise on an unselected drive line to improve the signal-to-noise ratio.

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Drive System with Noise Cancellation

In this drive system for a capacitor read-only storage, a controlled out-of- phase signal is generated to compensate for noise on an unselected drive line to improve the signal-to-noise ratio.

Separate transistors T1.... T6 drive corresponding word lines W1... W6. Consecutive word lines are paired and, normally, all transistors are off. Each pair of W's is charged substantially to supply voltage +V via respective resistors Rc and diodes D.

To select a word line, e. g., W2, a positive signal is supplied to the base of T2 to turn it on. W2 potential goes to ground and a strong signal is generated in sense lines S1 and S3, capacitively coupled to W2. However, capacitor Cf1 is unable to prevent a small voltage drop at X, which causes a corresponding voltage drop and a consequent noise signal in the associated W1.

To improve the signal-to-noise ratio, the common ground plane G for sense amplifiers SA is connected to the drive system common ground DG via a resistor
Y. Across this is provided a signal of opposite polarity that is subtracted in substantially equal amounts from both the main signal and noise signal.

Thus, if the main signal has an amplitude of 10 mv and the noise signal has an amplitude of 5 mv, the signal-to-noise ratio is 2 to 1. However, if the resistor provides a subtractive signal of 4 mv, the main signal becomes 6 mv and the noise signal only 1 mv, providing an improved signal-to-noise ratio of 6 to 1.

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