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Browse Prior Art Database

Domino Clocking Scheme to Reduce Clock Loads

IP.com Disclosure Number: IPCOM000118048D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Singh, RP: AUTHOR

Abstract

The present day microprocessors are getting faster and use either Dynamic logic which is self-resetting or Domino logic for Complementary Metal-Oxide Semiconductor (CMOS) based machines. Domino logic is fairly common and uses clocks to reset while self-resetting uses the output of its block to reset itself. In Domino logic, clocks are used extensively.

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Domino Clocking Scheme to Reduce Clock Loads

      The present day microprocessors are getting faster and use
either Dynamic logic which is self-resetting or Domino logic for
Complementary Metal-Oxide Semiconductor (CMOS) based machines.
Domino logic is fairly common and uses clocks to reset while
self-resetting uses the output of its block to reset itself.  In
Domino logic, clocks  are used extensively.

      Fig. 1 shows traditional Domino clock circuit and Fig. 2
describes the new approach.  In Fig. 1, T1, the Ground (GND)
interrupt device is at the bottom of the tree.  In Domino logic,
reset and evaluation depend on the system clock.  The data usually
comes from a static register and true/complements are generated at
local level to save space (otherwise you may have to run true and
complement signals from the register).  So at the very first stage,
Clock (CLK) is the latest arriving signal since the data coming in is
static and has to be  valid before we evaluate.  The new approach
uses this criteria and puts  the GND interrupt device T1 at the top
of the tree rather than at the bottom of the tree as shown in Fig. 2.
If the tree is long, device width of T1 does not need to be as big as
it would have been in Fig. 1.  Since CLK is the latest arriving
signal and T1 is sitting at the  top of tree, evaluation time
decreases.  Also, T1 isolates the rest of  the capacitance that
Pre-charge Transistor (TPRE) has to precharge; so  the Reset time is
also fa...