Spectral-null pulse waveform for characterizing gain and phase distortion in devices with uncorrelated frequency translation or limited CW power capability

A test waveform for distortion characterization, denoted Spectral-Null PULFe (SNP), is proposed whose time domain envelope approximates a low duty cycle rectangular pulse, but whose spectrum contains a null at the central spectral line frequency. This spectral line is regenerated by intermodulation distortion in a device under test. The resultant C-I ratio, together with the amplitude compression mea& at the pulse peak, may he mapped to AM-PM conversion at the peak amplitude. The technique does not require vector signal analysis and may thus be used to characterize frequency-converting devices with internal oscillators. The technique also permits probing of AM-AM and AM-PM deep into the compression region of high-power devices that cannot tolerate continuons high-level signals.