Browse Prior Art Database

BiCMOS Current Switch Speed-Up Circuit

IP.com Disclosure Number: IPCOM000121125D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Gabillard, B: AUTHOR [+3]

Abstract

This article describes the implementation of a set of devices accelerating the performance of the down-going transition of a current- switch circuit with emitter follower output in BiCMOS technology.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 84% of the total text.

BiCMOS Current Switch Speed-Up Circuit

      This article describes the implementation of a set of
devices accelerating the performance of the down-going transition of
a current- switch circuit with emitter follower output in BiCMOS
technology.

      In order to improve the current switch output down-going
transition in C0 (see the figure), a NFET (N0) with its gate
connected to the out-of phase output (C1) of the same current switch
is added between C0 output and the reference voltage of the current
switch; N0 becomes active when C1 goes up, without impacting C0
up-going transition because, in that case, C1 cuts N0 off.

      Another improvement of the global circuit is obtained by using
a NFET device (NEF) in the emitter follower output circuit and by
connecting its gate to the same out-of-phase current switch node
(C1).  By that method, current in NEF stays at its standby value when
the output (ATDG) goes up, and this current goes to its high value
when it is necessary to discharge ATDG node, because C1 goes up.
Thus, the current and the power dissipation are optimized.

      A preferred application of that technique is an Address
Transition Detection (ATD) circuit of a large and fast asynchronous
BiCMOS memory where the current switch circuit makes an OR function
of several Address Transition Detection Local (ATDL) positive pulses.
That circuit is followed by an internal clock generation circuit
which generates pulses from the down-going transition o...