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Timing Circuit with Feedback

IP.com Disclosure Number: IPCOM000083287D
Original Publication Date: 1974-Oct-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Luckett, GC: AUTHOR [+2]

Abstract

In a semiconductor memory circuit, a chip select CS pulse is utilized to select a desired chip. In a memory cell in which stored information leaks during chip select time, it is desired to limit the time of occurrence of the chip select pulse, which is accomplished by the present circuit.

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Timing Circuit with Feedback

In a semiconductor memory circuit, a chip select CS pulse is utilized to select a desired chip. In a memory cell in which stored information leaks during chip select time, it is desired to limit the time of occurrence of the chip select pulse, which is accomplished by the present circuit.

The circuit illustrated consists of N-channel field-effect transistors and operates in accordance with the illustrated wave form. Prior to selecting a desired chip, the select pulse and the restore pulse R are at their up levels while the chip select CS signal is at ground, thereby keeping node A at an up level and feedback node B at a down level. Transistors T3, T5, and T2 are on while transistors T1 and T4 are off. It is the purpose of transistors T3, T4, and T5 to suppress noise on the feedback node B.

When the select pulse drops to ground, the timing circuits 10 generate the required timing pulses for the chip. R discharges to ground and CS charges to the +V potential. In the interval between the select pulse dropping to ground and the CS pulse rising, T5 is on holding the feedback node B to ground.

The impedance of T1 is much less than the impedance of T5 so, as CS rises, the feedback node B also rises to its up level. The feedback node B turns on T4 discharging node A to ground which turns T5 off. As the feedback node B rises, the timing circuits return to their standby condition with R up and CS down.

The impedance of T3 is much higher than th...