resistors; internal inductance and capacitance

Thread Starter

ronsimpson

Joined Oct 7, 2019
705
I am working on 500mhz signals. At these frequencies the 0.05pF of capacitance in a SMD resistor adds up. Today I am fighting inductance of resistors. Most data sheets say nothing about inductance and some just say “low inductance”. One sheet said “0.5 to 5nH” depending on resistance value.

Is there information on inductance verses resistor size? The real question; is it better to use one 1W resistor, four 1/4W resistors in parallel or 30 small 0603 in parallel. (paralleling reduces inductance)
 

Papabravo

Joined Feb 24, 2006
13,922
0201 & 0402 parts are smaller than flyspecks in the pepper, but they have lower inductance.
Hope you have a good VNA to characterize ALL your parts
 

Thread Starter

ronsimpson

Joined Oct 7, 2019
705
Hope you have a good VNA to characterize ALL your parts
My network analyzer does not go high enough and the "company" is just starting to let engineers in to use the good stuff.
0402 parts are smaller than flyspecks in the pepper, but they have lower inductance.
Question: If I have 40 of the 0402 parts in parallel the trace inductance is high. OR I can use one big 2W resistor where the resistor has too much inductance but the traces are 5mm wide. I am thinking that at the end it will not make much difference.
 
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