Motorola Corporation

Samuel E Alexander

George P Hoekstra

Lal C Sood

Alan Richard Bormann

An integrated circuit comprises a chip containing electric circuits in a package with leads. The chip receives power via the leads. The leads have inductance so that when there is a change in current flow (di/dt) through a lead there is a voltage which is developed between the end of the lead and the chip which can cause the chip to either malfunction or function poorly. The highest di/dt is generally caused by an output buffer that changes the logic state of its output. The typical output buffer has a pair of driver transistors that provide one of a logic high or logic low. The di/dt generated by these transistors is controlled by controlling the voltage on the gate or base of the transistor which is providing the particular logic state. This control is responsive to the magnitude of the power supply voltage. An impedance which varies in resistance with supply voltage is placed in series between the positive power supply terminal and the gate or base of the output transistors.

Output buffer for improving di/dt

In a static random access memory in which the array is comprised of MOS transistors and at least some of the peripheral circuits are comprised of bipolar transistors, the bit lines and data lines are precharged to a base to emitter voltage drop (i.e. one Vbe) below the positive power supply voltage. This increases cell stability. Additionally, Vbe varies comparatively little over process. Additionally, precharging the bit lines and data lines to a Vbe below the positive power supply voltage allows for the use of a high speed bipolar differential amplifier in its optimum operating range as the first stage sense amplifier.

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Austin, TX, United States of America

Samuel E Alexander