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Push-Pull Bipolar Memory Array Driver

IP.com Disclosure Number: IPCOM000061480D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Flaker, RC: AUTHOR [+2]

Abstract

A circuit is provided which takes advantage of the stored charge of a pnp bipolar transistor in a push-pull driver to provide current for both the pull-up and pull-down operations of word lines. This additional current improves a Harper cell array driver performance in an unclocked mode and reduces the power required by a factor of about two. Word lines of a memory array are selected by a word decode matrix indicated in the figure. The voltage difference between VR1 and VR2 is set at two and one-half npn base-emitter diode drops by design. Current (I select) is steered from the decoder to a push-pull word driver and turns on transistors T2 and T3. Transistor T6 turns off since the voltage difference between node 1 and VR2 is reduced to one and one-half diode drops.

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Push-Pull Bipolar Memory Array Driver

A circuit is provided which takes advantage of the stored charge of a pnp bipolar transistor in a push-pull driver to provide current for both the pull-up and pull-down operations of word lines. This additional current improves a Harper cell array driver performance in an unclocked mode and reduces the power required by a factor of about two. Word lines of a memory array are selected by a word decode matrix indicated in the figure. The voltage difference between VR1 and VR2 is set at two and one-half npn base-emitter diode drops by design. Current (I select) is steered from the decoder to a push-pull word driver and turns on transistors T2 and T3. Transistor T6 turns off since the voltage difference between node 1 and VR2 is reduced to one and one-half diode drops. Emitter follower transistor T5 pulls up the word top and word bottom lines to select the memory cells. Current through resistor R2 and transistor T4 at this time could be minimized by connecting resistor R2 to a potential which is one-half Vbe more positive than VR2. When a different word line is selected, the I select current is switched to that word line and T2 shuts off. Current from resistor R1 turns on T4 and T6. T5 is turned off by T4 and the stored charge in the emitter-base junction of pnp transistor T3 is the source of overdrive current to the base of T6, which results in a rapid word line deselect. It can be seen that a pnp transistor T3 is used in a push...