Elimination of Systematic Error in the Measurement of Group Delay of Frequency Convertor

The influence of spectral leakage is analyzed theoretically when the two-tone method and the all-phase discrete Fourier transformation (apDFT) are utilized to measure the group delay of a frequency convertor. Owing to the spectral leakage, the spectral lines of the two tones interact, and the interaction arouses errors in the measurement of group delay. Then, an I/Q method is put forward to eliminate the interaction. Simulations with a frequency convertor demonstrate the feasibility of the I/Q method in eliminating the interaction.