Patent ID: 7414411

Claim:
A method of calibrating a signal path of a signal analysis system comprising the steps of: connecting a first probe P 1 to a device under test and acquiring sets of samples in the time domain of the signal under test from the device under test via a first probe signal path SP 1 including a plurality of selectable impedance loads, with the first probe signal path SP 1 for each set of samples having a selected impedance load of the plurality of selectable impedance loads; converting the sets of samples in the time domain of the signal under test to spectral domain representations; characterizing transfer parameters of the device under test within a spectral domain from the spectral domain representations; calculating an open circuit voltage (v open P 1 (f)) of the device under test in the spectral domain using the characterizing transfer parameters of the device under test; connecting a second probe P 2 to the device under test and acquiring a set of measurement samples in the time domain of the signal under test from the device under test via the first probe P 1 of the first probe signal path SP 1 including one of the selected impedance loads; converting the plurality of measurement samples in the time domain to a spectral domain representation (v meas P 1 (f)); computing an equalization filter adapted to compensate for loading of the device under test caused by the first and second probes, P 1 and P 2 , using the spectral domain open circuit voltage (v open P 1 (f)) and measurement samples (v meas P 1 (f)); acquiring at least an additional set of samples of the signal under test from the device under test in the time domain via the first probe P 1 of the first probe signal path SP 1 including the selectable impedance load of the set of samples used for acquiring the measurement samples; converting the additional set of samples of the signal under test from the time domain to a spectral domain representation; and processing the spectral domain representation of the additional set of samples using the computed equalization filter to effect thereby an open circuit voltage {circumflex over (v)} open P 1 (f) having a reduction in signal error attributable to the measurement loading of the device under test caused by the first and second probes, P 1 and P 2 .