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Two-device Sensing Cell for Cmos Memory

IP.com Disclosure Number: IPCOM000059841D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Jorgensen, WA: AUTHOR [+2]

Abstract

A two-device sense circuit for static read/write memory is comprised of one P-channel 110 and one N-channel device 111. The gate and drain of the p channel device 110 are connected to the bit lines of the memory cell via the bit select circuitry. The source of device 110 is connected to the output buffer 5 and to the drain of pull-down device 111.

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Two-device Sensing Cell for Cmos Memory

A two-device sense circuit for static read/write memory is comprised of one P-channel 110 and one N-channel device 111. The gate and drain of the p channel device 110 are connected to the bit lines of the memory cell via the bit select circuitry. The source of device 110 is connected to the output buffer 5 and to the drain of pull-down device 111.

The bit lines 8 and 9 are precharged high during a memory restore. Device 111 is "on", keeping node 10 at ground. During a read operation, device 111 is turned "off" and a memory cell is addressed, causing one of the two bit lines 8 and 9 to discharge. If bit line 9 discharges on threshold voltage or more below bit line 8, device 110 will turn "on", transferring the high voltage level of bit line 8 to sense node 10, and a logic "1" is read. However, if bit line 8 discharges one threshold or more below bit line 9, device 110 will be kept off, sense node 10 will remain low, and a logic "0" is read.

The two-device sense circuit detects a voltage difference equal to or greater than the threshold voltage of the p channel device, rather than waiting for one of the bit lines to discharge completely to ground. Furthermore, the voltage difference between bit lines is sensed, allowing correct sensing of the state of the memory cell even if the bit lines are not completely precharged high during a memory-restore cycle. Therefore, the two-device sense circuit provides a simple solution to sen...