Compensation of Time-Domain Waveforms by Applying the Complex Transfer Function of a Current Probe in the kHz-MHz Range

Abstract

The advance in power converters is demanding a higher set of measurement tests, in large bandwidths and with waveform monitoring in the time domain. Current probes contain many advantages for such measurements, but the direct use in the time domain is not straightforward due to the non-constant transfer impedance, which can cause critical distortion on the probe output. This work demonstrates through laboratory measurements an FFT-based technique for compensation of signals measured in the time domain. By applying the current probe’s transfer function together with the signal spectra of its measured current, the applied voltage can be recovered and the supply current can be estimated. Also, the calibration steps for measurement of the probe’s complex transfer function are detailed, comparing three different approaches. The results have shown excellent accuracy with the measurements for the compensation of a simple triangular signal in the kHz range.