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Browse Prior Art Database

Super Buffer for Domino BiCMOS

IP.com Disclosure Number: IPCOM000120719D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 56K

Publishing Venue

IBM

Related People

Cook, PW: AUTHOR [+2]

Abstract

Disclosed is an improvement to "domino" logic circuits in which a low power bipolar driver is added to enhance the pull-up performance of the circuit.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 66% of the total text.

Super Buffer for Domino BiCMOS

      Disclosed is an improvement to "domino" logic circuits in which
a low power bipolar driver is added to enhance the pull-up
performance of the circuit.

      "Domino" logic circuits (Fig. 1) offer, in appropriate
circumstances, performance advantages over other logic families
because the complex logic "tree" operates to discharge a pre-charged
node from a high to a low:  for MOS technologies, this is the fastest
transition that can be done for a given "tree".  For CMOS
technologies, the speed-up is even greater, as the loading on the
driving stage is approximately one-half what it would be driving a
CMOS circuit, with both N-channel and complementary P-channel trees.

      The output of a normal domino circuit is taken through an
inverter, as shown in Fig. 1.  This is necessary as a requirement for
proper operation of the circuit is that all domino outputs be at
ground during the pre-charge time. Thus, the inverter always acts to
pull up the circuit's output.  This, unfortunately, involves for CMOS
a P-channel device whose mobility - and, therefore, rate of rise - is
limited.

      In this invention, the inverter is augmented as shown in Fig. 2
by the addition of an NPN emitter follower using an N-channel FET as
emitter load.  The base of the NPN in connected to the inverter
output, and the gate of the N-channel FET is connected to the
inverter input.  With this connection, the emitter follower pulls the
output no...