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CMOS Hysteresis Receiver

IP.com Disclosure Number: IPCOM000112693D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Cao, T: AUTHOR [+3]

Abstract

A CMOS hysteresis receiver provides signal integrity for a noisy environment, especially when circuits operate at very high speeds. This type of circuit offers better noise tolerance by shifting the switching threshold voltage of devices.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

CMOS Hysteresis Receiver

      A CMOS hysteresis receiver provides signal integrity for a
noisy environment, especially when circuits operate at very high
speeds.  This type of circuit offers better noise tolerance by
shifting the switching threshold voltage of devices.

      For rising transition, Vtr (rising transition switching
threshold) is more than Vdd/2; noise margin is from 0V to that of
point Vtr.  For fall transition, Vtf (falling transition switching
threshold) is less than Vdd/2; noise margin is from Vdd to that point
Vtf.

      The Figure shows the CMOS hysteresis receiver with an inhibit
signal.  The receiver input stage consists of pass devices Q5
(p-device) and Q10 (n-device).  The gates of these pass devices are
controlled by the receiver inhibit signal RI.  When the signal RI is
logic '1' (Vdd), the pass devices are 'on' and 'in' information is
passed through them and goes to the input of CMOS inverter INV1.
When RI is logic '0' (Gnd), the pass devices Q5 and Q10 are 'off' and
the node A is in an undetermined state.  In order to put in the known
state for testability purposes, a device Q6 (p-device) is used on
node A and it is turned 'on' whenever the RI signal goes to logic '0'
state causing node A to go to logic '1' state.

      As shown in the Figure, shifting switching threshold is
achieved by INV3.  When 'in' goes from logic '0' to logic '1',
n-device of INV1 begins to turn on.  But that n-device has to
struggle with the p-d...