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Noise Reduction for Bidirectional Bus Drivers with Impedance Match

IP.com Disclosure Number: IPCOM000118111D
Original Publication Date: 1996-Sep-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Frech, R: AUTHOR [+4]

Abstract

Disclosed is a noise reduction for bidirectional driver/receiver books, which are matched to the characteristic line impedance by a resistor. The idea is to put the serial resistor of the driver into the Bidirectional Bus (BIDI) path. If the line is quiet, the noise margin is increased due to dissipating a part of the coupling energy at the serial resistor before the receiver.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 73% of the total text.

Noise Reduction for Bidirectional Bus Drivers with Impedance Match

      Disclosed is a noise reduction for bidirectional
driver/receiver books, which are matched to the characteristic line
impedance by a resistor.  The idea is to put the serial resistor of
the driver into the Bidirectional Bus (BIDI) path.  If the line is
quiet, the noise margin is increased due to dissipating a part of the
coupling energy at the serial resistor before the receiver.

      The bidirectional driver is shown in Fig. 1.  It consists of a
driver and a receiver part.  To cancel reflections, the driver is
matched to the characteristic impedance of the transmission line by a
serial resistor.  This resistor can be placed either directly after
the driver  output (position 1) or in the BIDI path of the receiver
(position 2).

      Because the receiver input is purely capacitive, position
2 of the serial resistor has no significant impact on the driving
line.  However, it will be shown that for an incoming wave, this
resistor can increase the noise margin by dissipating energy of a
coupling noise signal and increasing the signal integrity of the
system.  The reduction of the signal amplitude is acceptable for an
active signal, because there is a voltage doubling at the receiver
input due to the capacitive load.

      The simulation results are shown in Fig. 2 for the Monet
BSN-STC net.

      This net is going from the Multi-Chip Module (MCM) via a board
transmission lin...