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Read/ Write Scheme For Bipolar Random Access Memories Using Schottky Coupled Cells

IP.com Disclosure Number: IPCOM000048996D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Dussault, RD: AUTHOR [+2]

Abstract

Schottky coupled memory cell designs have separate circuits for bit selection and for writing the cells (Fig. 1). By using a tri-state bit decode level, one can perform the read and write functions using one simplified circuit. This provides a reduction in chip area and power.

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Read/ Write Scheme For Bipolar Random Access Memories Using Schottky Coupled Cells

Schottky coupled memory cell designs have separate circuits for bit selection and for writing the cells (Fig. 1). By using a tri-state bit decode level, one can perform the read and write functions using one simplified circuit. This provides a reduction in chip area and power.

Fig. 2 is a schematic representation of the disclosed read/ write scheme. Transistors T1 and T2 and resistors R1 and R2 define the read/ write circuitry needed per one bit line pair. Bit line nodes Bl and BR are connected to the Schottky-coupled cells.

During a read mode, if the cell is unselected, the bit decode level is low and transistors T1 and T2 are off. If the cell is selected, the bit decode level is clamped to an intermediate state by a voltage provided from the write gate circuit. Reference is made to the preceding article. Transistors T1 and T2 turn on, and the bit line voltages are determined by the selected cell current flow through the bit line transistors. This current flow may be differentially sensed at the collectors of transistors T1 and T2 to determine the state of the cell.

During a write mode, the bit decode level is at a high state while simultaneously current is pulled through either bit line resistor R1 or R2 by the Data-In circuit. Pulling current through either resistor R1 or R2 will decrease the voltage level at BL or BR, turning off the outboard Schottky diode. This allows write c...