Browse Prior Art Database

Current-Driven Self-Terminated MOS Receiver

IP.com Disclosure Number: IPCOM000105632D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Dougherty, J: AUTHOR [+2]

Abstract

Computer clock and data signals are operating at very high frequencies and are often distributed on several levels of electrical packaging as low-level, differential signals. Disclosed is a circuit designed to receive a low-level, differential signal and generate as its output, a single-ended signal at CMOS levels.

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Current-Driven Self-Terminated MOS Receiver

      Computer clock and data signals are operating at very high
frequencies and are often distributed on several levels of electrical
packaging as low-level, differential signals.  Disclosed is a circuit
designed to receive a low-level, differential signal and generate as
its output, a single-ended signal at CMOS levels.

The driver is connected to inputs A0 and A1 (Figure).  The driver
switches, pulling current through device T1, and turning off current
to device T2.  T3 mirrors the current in T1 which is then conducted
by devices T5 and T6.  Since the driver is not conducting current at
input A1, T2 on conducts the trickle current from T8.  T4 mirrors the
current in T2 and T8.  Since T3, and correspondingly T6, are
conducting significantly more current than T4, the output node 2 is
pulled low.

When the driver switches in the other direction, it pulls current
through device T2 and turns off current to device T1.  T4 mirrors the
current in T2.  T1 conducts the trickle current from T7 which is then
mirrored by T3, T5, and T6.  Since T4 is conducting significantly
more current than T6, the output node 2 is pulled high.

The main function of T7 and T8 is to bias the input terminating FETs,
T1 and T2, at a point on the device curve where their impedance is
adequate to minimize ringing of the zero current to full current
transition of the driver.  Care must be taken so that T7 and T8 do
not conduct more current than T1-T3...