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Design >> RF Design >> Capacitive loading of input probe pad+coax cable+sig gen
https://designers-guide.org/forum/YaBB.pl?num=1400932983

Message started by mixed_signal on May 24^th, 2014, 5:03am

Title: Capacitive loading of input probe pad+coax cable+sig gen
Post by mixed_signal on May 24^th, 2014, 5:03am

Hi,
I am using RF probes to introduce 2.4GHz to a matching network (ONCHIP) from a signal generator. I want to know approx. parasitic capacitive loading (paralle C from input to ground) at the input due to signal generator+coax+rF probes. I want to design matching network accordingly to account for this.

Title: Re: Capacitive loading of input probe pad+coax cable+sig gen
Post by loose-electron on May 26^th, 2014, 11:49am

For those frequencies you need to design a 50 ohm terminated cable connection on your board and input port on the IC that is designed to handle that 50 ohm cable signal.

By probe methods? Not with any accuracy.

Title: Re: Capacitive loading of input probe pad+coax cable+sig gen
Post by mixed_signal on May 26^th, 2014, 10:35pm

Hi loose-electron
By probe methods I mean RF probes for probing die (onchip). I have pads on silicon where the probe can be landed. I am worried about the loading of the RF probe? Is it capacitive ? approx. value?

Title: Re: Capacitive loading of input probe pad+coax cable+sig gen
Post by loose-electron on May 30^th, 2014, 3:07pm

probes available for a probe station are pretty well specified relative to their input loads.

Generally I avoid probes to a wafer its just to awkward to do and does not yield good repeatable results.