Browse Prior Art Database

Immunizing Strobe Signals to Crosstalk

IP.com Disclosure Number: IPCOM000088947D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Langdon, GG: AUTHOR

Abstract

This device relates to noise suppression, and more particularly to the prevention of spurious circuit turn-ons and turn-offs caused by noise induced on a path terminating in the circuit. What is proposed is the insertion of a pair of tandem-connected edge-triggered (D type) flip flops synchronized to a common clock with a suitable AND/OR combining network therebetween. This arrangement permits transitions on the path to be gated through to the circuit only upon another transition occurring exactly "s" seconds later, where "s" is a fixed multiple of the clock period.

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Immunizing Strobe Signals to Crosstalk

This device relates to noise suppression, and more particularly to the prevention of spurious circuit turn-ons and turn-offs caused by noise induced on a path terminating in the circuit. What is proposed is the insertion of a pair of tandem-connected edge-triggered (D type) flip flops synchronized to a common clock with a suitable AND/OR combining network therebetween. This arrangement permits transitions on the path to be gated through to the circuit only upon another transition occurring exactly "s" seconds later, where "s" is a fixed multiple of the clock period.

Referring to Fig. 1, there is shown a usual environment of paths and terminating circuits, i.e., an equipment interface. The interface may be of the demand/response type, where control signals in one direction cause data to be sent in the other direction.

The circumstances which favor the proposed arrangement are the presence of:

(1) crosstalk due to a signal change enduring for no more than a predictable time (e.g., Tmin),

(2) where the minimum pulse widths of the strobe signals and reset signal exceed 2 Tmin, and

(3) where the strobe signals can be delayed on the adapter side of the interface by the amount 2 Tmin.

The solution to the problem is shown in Fig. 2. This solution is applied only to the strobe or reset signals of the interface and need not be applied to the data or address lines which are gated by the strobes. The circuit behaves as follows. When ass...