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Improved Large Scale Integrated Voltage Source

IP.com Disclosure Number: IPCOM000080041D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Cox, DT: AUTHOR [+3]

Abstract

When designing large-scale integrated field-effect transistor (FET) circuits, the resistivity of devices on any one chip will tend to be substantially uniform, but relatively large variations in resistivity can be expected between devices on different chips. Reliable system operation is adversely affected by resistivity variations from chip-to-chip. For example, high resistivity causes smaller saturation currents to flow through devices 11 and 12, but also raises the turn on threshold voltage Vt of devices 13 and 14 of the memory latch cell in the figure. Therefore, an array supply voltage Va must be chosen high enough to insure reliable operation of the highest resistivity chip. The lowest resistivity chip connected to this same supply Va will then draw substantial current and dissipate excessive power.

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Improved Large Scale Integrated Voltage Source

When designing large-scale integrated field-effect transistor (FET) circuits, the resistivity of devices on any one chip will tend to be substantially uniform, but relatively large variations in resistivity can be expected between devices on different chips. Reliable system operation is adversely affected by resistivity variations from chip-to-chip. For example, high resistivity causes smaller saturation currents to flow through devices 11 and 12, but also raises the turn on threshold voltage Vt of devices 13 and 14 of the memory latch cell in the figure. Therefore, an array supply voltage Va must be chosen high enough to insure reliable operation of the highest resistivity chip. The lowest resistivity chip connected to this same supply Va will then draw substantial current and dissipate excessive power.

By using a series resistor 10 external to each chip, a common higher voltage +V supply can be used for all chips. Higher resistivity chips will draw less current through their resistor 10 and thus have a higher Va, as required for reliable latch operation, while low-resistivity chips will have a lower Va and thus dissipate less power than they would have if supplied from a fixed higher voltage Va supply. Resistor 10 can have the same resistivity value for all chips.

Because the bit sense lines on each chip are quite long, substantial leakage currents I1 are drawn by the sense lines. These leakage currents I1 tend to ...