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Switchable Reference Level Driver

IP.com Disclosure Number: IPCOM000084237D
Original Publication Date: 1975-Oct-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Olderdissen, U: AUTHOR [+4]

Abstract

Depicted within the broken line in the drawing is the circuit of a switchable reference level driver. The driver has particular utility when employed in a monolithic memory.

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Switchable Reference Level Driver

Depicted within the broken line in the drawing is the circuit of a switchable reference level driver. The driver has particular utility when employed in a monolithic memory.

The objective is to provide low impedance and low-power consumption level drivers, which will track and be equal to an input voltage supplied from a high- impedance source. The driver has a fast response time. The driver may be switched from another source, represented by switch S1, without effecting the high-impedance source.

In order to achieve an input voltage equal to the output voltage when switch S1 is open, it requires: Vbe (Tl) = Vbe (T2) Vbe (T3) = Vbe (T4) Then V (output) = V (input) - Vbe (T1) + Vbe (T2) + Vbe (T3) - Vbe (T4) = V (input)

In a monolithic memory application, the output voltage provides a reference voltage to the sense amplifier.

When switch S1 is closed, the output voltage is equal to the base voltage of transistor T4 less the Vbe of transistor T4.

The purpose of resistor R2 is to insure that when switch S1 is closed, transistor T3 is switched off, and transistor T2 remains in a conductive condition with about the same current as when switch S1 is open.

This switching action accomplishes the following: One, the emitter current through transistor T1 will increase slightly, and the base current drawn from the high-impedance source will remain almost constant since Ib (T1) = Ie (T1) /(beta + 1). Secondly, transistor T2 is not cut off wh...