Method for reducing multiple reflections in the long line

Assume that I would like to connect a fast digital signal to a gate through a relatively long line. And assume that we can model the line as a transmission line and the gate as an open circuit. Can anyone suggest a method to reduce multiple reflections in the long line to minimize the chances of erroneous communication???

Re: Question

A digital signal is very broadband. Therefore a quarterwave transmission line transformer will not work, since it is a narrowband impedance match.

But, the basic answer is correct, at the gate end of the long transmission line, the energy travelling toward the load has to see the same impedance as the trasmission line. In other words, if it is a transmission line with 50 ohm characteristic impedance, the load on the line has to look like 50 ohms +j0 ohms.

Assuming the gate is much higher impedance, one method would be to drop a resistor across the line in parallel with the gate.

Line drivers/line receivers do this. Typically the transmission line is 100 ohm characteristic impedance (twisted pair) and you use an actual 100 ohm chip resistor at the input to the line receiver. The line receiver (op amp comparator) then translates the voltage into one that the gate can recognize.

PECL type gates use a terminating resistor on lines for this same reason--to place a nice resistive load at the end of the transmission line.

One could actually measure the gate impedance and try to do a broadband reactive element match to it. I have never heard of anyone actually doing that, however.