18-40 GHz broadband frequency synthesizer technique

The paper shows how the maximum frequency coverage of an existing frequency synthesizer system can be extended to 40 GHz. The existing synthesizer system provided standard frequency coverage of 0.1-18 GHz via modular single octave and multioctave band RF sources. This frequency range is extended from 18 to 26.5 GHz and 26.5 to 40 GHz by development of two additional modular plug-in RF sources. The paper discusses the theory of the dual phase-locked scheme and the performance data obtained by using this system. Discussions of various approaches and the advantages/disadvantages of each are presented. The proposed synthesizer system may be programmed either manually by a front panel keyboard or remotely by digital commands. The stable spectrally-pure output signal of this synthesizer is obtained by phase-locking a fundamental YIG-tuned transistor or Gunn diode oscillator in the RF source to an oven-enclosed reference oscillator in the mainframe.