Distortion Characteristics of Injection Locked Gunn and Impatt Diode Oscillators

The distortion characteristics of injection locked Gunn and Impatt diode oscillators are investigated both theoretically and experimentally. For FM signal transmission, the distortion is determined mostly by the derivated characteristics: group delay, AM-to-PM conversion and AM compression. Due to nonlinearity of diode susceptance, the group delay and AM-to-PM conversion characteristics are unsymmetrical. At the lower frequency end of the locking range, the distortion is rather high. Minimum distortion is obtained at a frequency higher than the band center. With the same output power, the distortion of an injection locked oscillator is smaller than that of a stable amplifier.