Hello,
I searched on guard rings but i didn't find an answer...
I am using guard traces to protect a very high impedance line from influence from conductance across the PCB surface. Everything I read talks about guard rings. However, is it important for any reason that they be a ring? How about simply a trace that ends without looping back?
This is a very low frequency signal, but very high impedance. I am buffering it with a voltage follower using an op amp with very low input bias current. I am guarding it with the output of the follower, which will approach the same potential as the input signal. It is much better to my layout, however, to run the guard trace between the input pin and the power supply pin to the op amp, but *not* to loop it all the way around. I figure if it gets in between the power and input pin, that's doing the function of protecting the input signal from any conductance on the PCB or surface contaminants.
Any disagreement on that?
I searched on guard rings but i didn't find an answer...
I am using guard traces to protect a very high impedance line from influence from conductance across the PCB surface. Everything I read talks about guard rings. However, is it important for any reason that they be a ring? How about simply a trace that ends without looping back?
This is a very low frequency signal, but very high impedance. I am buffering it with a voltage follower using an op amp with very low input bias current. I am guarding it with the output of the follower, which will approach the same potential as the input signal. It is much better to my layout, however, to run the guard trace between the input pin and the power supply pin to the op amp, but *not* to loop it all the way around. I figure if it gets in between the power and input pin, that's doing the function of protecting the input signal from any conductance on the PCB or surface contaminants.
Any disagreement on that?