[TriEmbed] Scopes, probulators, and matchmaking

[Pete Soper]

On 07/27/2018 12:40 PM, Brian via TriEmbed wrote:

> 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.
Yes, I said that. Maurico's scope has so little bandwidth this issue is 
irrelevant, but I thought it might be of interest to others.
>
>
> 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.
Yes, altering "DC impedance" would be a hell of a challenge.
>
> Suffice it to say, impedance matching for signals involving both AC 
> and DC components is no simple ordeal!
>
> -B
>
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