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Measurements >> RF Measurements >> Measurement wideband differential signal path
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Message started by Visjnoe on Mar 13^th, 2010, 1:50am

Title: Measurement wideband differential signal path
Post by Visjnoe on Mar 13^th, 2010, 1:50am

Dear all,

I'm thinking about the test interface of a wideband (~500MHz) IQ differential signal path.
What do you consider the best approach to test this, both from the on-chip as off-chip perspective?

I was considering the use of (tapered) source followers to drive the signal off chip (probably will have to drive a few pF's) and than to measure it using an active probe.

Another option would be to feed it (also using source followers) into an off-chip voltage buffer/amplifier. Unfortunately, it's apparently hard to find components that provide a high input impedance + the required bandwidth. Furthermore, most datasheets don't mention input capacitance.

Specifically, on the on-chip test buffers (~source followers) do you see any specific disadvantage/advantage of using DC coupling or AC coupling?

Regards