[SI-LIST] Re: Probe impedance effect at high frequency
- From: "Steven Kan" <steven@xxxxxxxxxxxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Thu, 16 Mar 2006 16:33:34 -0800
> From: <TerenceHsieh@xxxxxxxxxxxx>
>
> I have a problem about differential probe. When measure a DUT with low
> output impedance, it is appropriate to use high impedance probe. If the
> probe impedance is ten times than DUT, the probe impedance could ignore
> and the measurement result will more accurate. I checked the technical
> note of differential probe P7380. The DC impedance of P7380 is 100K ohm
> and this is larger enough for most DUT. However, the impedance is just
> about 300 ohm at about 2GHz. If I want to measure a DUT that operate at
> 1.25GHz (PCIE Gen.1) and the differential impedance of DUT is 100 ohm.
> Could P7380 measure accurate result? How the low AC Loading of probe
> affect the result? Thanks
Terence,
We are about to introduce a 3+ GHz probe that should handle your 1.25 GHz
application just fine. We don't have any formal specifications for it yet,
but we have an early draft of a web page and a photo, here:
http://www.pulseresearchlab.com/products/gigaprobe/
These probes are only $55 (for U.S. delivery), so it wouldn't be too
expensive to try out. It does require a 50 Ohm cable, but most people have
these lying around.
We'll post 'scope shots shortly.
--
Steven Kan (p) 310-515-5330 x24
Pulse Research Lab (f) 310-515-0068
1234 Francisco St., Torrance, CA 90502 (c) 818-620-3062
mailto:steven@xxxxxxxxxxxxxxxxxxxx
http://www.pulseresearchlab.com
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