Technical Guide to Delay Lines
1. Introduction
Delay Lines are used in computers, both general and personal, and other equipment for automation, medical, IC testing, video, hard disc drivers, etc., for timing and phase adjustments. Therefore, it is necessary to have a variety of delay lines. TOKO is introducing a full line of Delay Lines to meet with your needs.
2. Parameters and Measurements
2-A Impedance and Terminations
For matching and termination, pure resistors equivalent to the characteristic impedance; Zo, are used.
R1 R2 : Input Matching Resistance : Terminating Resistance ( = Zo) RL : Output Impedance of Signal Source Rg R1 = Rg R2 = Zo Zo – Rg Zo (Zo – Rg)
Rg
R2 R1
IN
Zo
OUT RL
GND
R1 = Rg R2 =
Zo Zo – Rg Zo (Zo – Rg)
Effect of unmatched resistances on the input waveform.
ZO > R L ZO = R L ZO < R L
TD=Total Delay Time
2TD
Terminating method of Delay Line with IC circuit. (Three typical methods are shown)
a. With ample driving power
5V R1 R ZO
b. Insufficient driving power
R2
R1 . R2 R1 + R2
ZO
R
ZO
c. Open collector driving method
Recommended layout for components Pattern layout with Delay Lines should be without use of additional inductors or capacitors. Furthermore, the receiving side at the output is preferably with high impedance.