Analysis and Calibration of the Amplitude and Phase Errors in High Time Bandwidth Product LFM Signal Generators

The possible sources of amplitude and phase errors are analyzed for digital LFM signal generators. The errors are classified according to their frequency. The amplitude and phase errors of the LFM signal generators using quadrature modulation technology are mapped into baseband. Then a method using complex coefficients FIR filters to calibrate the errors in digital domain is presented. This method is simplified by pre-distorting directly the stored waveform data for the direct digital waveform synthesis system. The error calibration method is applied to a practical system and the signal performance is significantly improved, proving that the method is easy to use and effective.