[TriEmbed] Scopes, probulators, and matchmaking

[Brian]

On 07/27/2018 10:37 AM, Pete Soper via TriEmbed wrote:

> A trimmer capacitor can be used to get matching just right
Technically speaking, a probe's trim cap is about adjusting the probe's 
own impulse response (the probe itself is an RC circuit with a time 
constant, and therefore has an impulse response).  Generally this is 
used during probe calibration with a 1 kHz reference square wave, and 
adjusted until the corners of the measured square wave are sharp with no 
ringing or excess damping.  Naturally this does affect the probe's 
impedance, but probably not in a useful range for Mauricio's particular 
need.

Also, capacitance in general primarily only affects AC impedance (an 
ideal capacitor's DC impedance is infinite; real capacitors have a 
leakage current but typically a very small one), so capacitance alone is 
not enough to effect proper impedance matching.

Suffice it to say, impedance matching for signals involving both AC and 
DC components is no simple ordeal!

-B