GaAs FET direct frequency-modulators for 42-GHz-band HDTV radio cameras and 7-GHz-band field pick-up transmitters

The design of a direct frequency-modulator with high modulation sensitivity is described. With a dielectric resonator, two hyper-abrupt-junction varactors, and a GaAs FET, this design achieves a modulation sensitivity greater than 20 MHz/V in a 42-GHz-band frequency modulator developed for HDTV (high-definition television) radio cameras. When this design is used in a 7-GHz-band frequency modulator for a field pick-up transmitter gathering emergency news, it provides an output power of 22 dBm, a differential gain of less than 3%, and a differential phase of less than 2 degrees . All transmitters using this frequency modulator have a high broadcast efficiency.<>