Neil,

     Thanks for the interest. My application is in an interface CCA between
     sonar transducers and a data acquisition processor CCA. There are a
     variety of opamp circuits on board, including regular inverting and
     non-inverting, as well as pseudo-differential circuits.

     My question concerning guard rings started off due to a requirement to
     minimize offsets, etc.. However, I am now unsure whether the circuit
     impedances I am dealing with are really high enough to warrant the use
     of guard rings. But, as always happens, my curiosity is piqued. So my
     question still stands.

     It seems that the question is general enough that the specific
     opamp/circuit involved is not that important. Whatever the circuit, it
     still remains that you have to connect to a node which is being
     guarded on every layer of the PCB. How is this done without breaking
     the guard on at least one layer?

     Hope you can help,

     Max.P.Harris
     Hardware Design Engineer
     Lockheed Martin Canada, Inc.


______________________________ Reply Separator _________________________________
Subject: Re: [TN] DES: Guard rings
Author:  Neil Diamond <[log in to unmask]> at smtp_gway