From: Ingraham, Andrew ([email protected])
Date: Wed Nov 01 2000 - 04:35:38 PST
DC block and AC coupling are essentially the same.
But a lot depends on where the terminations are. If the impedance to
terminate the line comes after the cap, then it is much more important to
have a low impedance to all useful harmonics, not only to faithfully couple
the waveform to the receiver, but also to terminate the line without a lousy
reflection coefficient. That is why DC block capacitors must have very wide
bandwidth; the (AC) termination is on the other side.
On the other hand, if the termination is before the cap, and the load seen
on the other (receiver input) side is a relatively hi-Z, then the cap's
impedance can be higher without adversely affecting either the coupling
efficiency or the reflection coefficient. What's important here is
impedance magnitude, not phase angle (inductive vs. capacitive).
**** To unsubscribe from si-list or si-list-digest: send e-mail to
[email protected] In the BODY of message put: UNSUBSCRIBE
si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
si-list archives are accessible at http://www.qsl.net/wb6tpu
This archive was generated by hypermail 2b29 : Tue May 08 2001 - 14:29:56 PDT