Browse Prior Art Database

Process Tracking Delay Element

IP.com Disclosure Number: IPCOM000105719D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Ueda, M: AUTHOR

Abstract

This article describes a CMOS delay element circuit whose delay characteristics is insensitive are process deviation.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 77% of the total text.

Process Tracking Delay Element

      This article describes a CMOS delay element circuit whose delay
characteristics is insensitive are process deviation.

      The switching speed of a transistor is dominated by delta L,
and therefore a process tracking strategy is needed to let devices
operate more quickly at the longer channel process corner (slower
case) and more slowly at shorter channel process corner (faster
case).  T3 and T8 in the figure and long channel devices that are
insensitive to process deviation, while T4 and T7 are short channel
devices which are sensitive to process deviation.  These devices form
a voltage divider and work as a process monitor.  As a result of the
difference in process dependence of these devices, T1 and T6 are
turned on strongly to slow the propagation of the signal when process
parameters deviate to the short channel corner.  When process
parameters deviate to the long channel corner, where devices work
more slowly, T1 and T6 are hardly turned on and the signal propagates
as if there were no feedback control.  MOS diode T2 and T5 are added
to prevent 'dead lock' of the feedback to insure functionality at any
condition.

      The Schmitt trigger circuit receives the delayed signal so that
propagation delay can be adjusted by the input threshold of Schmitt
trigger circuit.  The voltage divider is activated only during delay
operation that is controlled by delay input and output so as to
minimize the power consumption o...