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putting guard ring around resistor

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sharkies

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I am using TSMC 90nm PDK and I'm wondering if I should enable guard ring option for my poly resistor for my 1.9GHz divider. I'm actually confused if this would help at all. does guard ring help matching? What's the purpose of having guard rings in resistor? I would understand if it's guard ring for transistors..... but putting around resistors seem odd.

The only reason I can think of is to use the accurate rppoly_rf model that is provided by TSMC and it believe that one is measured with guard rings going around. Am I right?
and unltimately, is it necessary to use guard ring around resistors in my divider? don't wanna fix my layout.. ugh.... tired
 

You don't need a guard ring, unless you need screening from/against electromagnetic interference (internal as well as external, passive or active).
 

erikl,
What's the principle for this help to EMI?
Thanks.
 

leo_o2 said:
What's the principle for this help to EMI?
Click to expand...

For low-power resp. high-resistive device: to screen EMI from other nearby devices and wires.
For high-power resp. low-resistive (high-current) device: to screen EMI onto other nearby devices and wires.

Guard-ring to be connected to (AC) GND.

Screening of (or against) external RF interference would also need screening from above/below, but possibly for the whole chip/system.
 
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