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Cell Recovery Circuit

IP.com Disclosure Number: IPCOM000086295D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Heuber, K: AUTHOR [+5]

Abstract

In circuits with bipolar transistors for the storage cells and Schottky diodes as coupling elements the essential problem is that after selection the storage cells must be able to reach their standby potential within a very short time, in order to keep the cycle time as short as possible. for storage cells using PNP transistors as load resistors it is also essential that voltage VN used for the bases is very low. The standby current of such storages is a function of resistor R1. It is essential that in the case of large arrays the standby current be kept low, since this keeps the power dissipation rate equally low. But a low current results in a long cycle time. Thus each read or write operation is followed by a recovery phase.

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Cell Recovery Circuit

In circuits with bipolar transistors for the storage cells and Schottky diodes as coupling elements the essential problem is that after selection the storage cells must be able to reach their standby potential within a very short time, in order to keep the cycle time as short as possible. for storage cells using PNP transistors as load resistors it is also essential that voltage VN used for the bases is very low. The standby current of such storages is a function of resistor R1. It is essential that in the case of large arrays the standby current be kept low, since this keeps the power dissipation rate equally low. But a low current results in a long cycle time. Thus each read or write operation is followed by a recovery phase.

In this recovery phase the cell current is increased substantially over the standby state. This is achieved by switching on transistor T1 connected in series to resistor R2. Transistor T1 is switched on via transistor T2 which in its turn is series connected to resistors R4 and R3. When transistor T3 is switched on, potential VN is applied to the base of PNP transistor T1. Thus the magnitude of the increased current for thc recovery phase is determined via resistor R2. After completion of the recovery phase, transistor T1 must be switched off as quickly as possible.

To this end a network consisting of transistors T2, T4 and resistors R3 and R4 is used. As transistor T1 (T3 and T4 are off) is switched off, transistor T...