부산대학교 도서관

Low phase noise, good frequency stability over wide temperature range, tight initial frequency calibration and low power consumption of the signals sources are essential for many modern communication applications operating in UHF frequency band. The best sample of TCXO can provide good combination of these parameters only in 10/spl divide/50 MHz frequency band. A frequency translation technique should be applied to transform those signals in UHF band without phase noise degradation. UHF VCXO looked by PLL on a signal of 10 MHz TCXO allows to keep a good temperature stability and to achieve a phase noise level L/spl phi/(1 kHz) = -108 dBc/Hz at 1 GHz carrier frequency. The circuit optimization allows decreasing an influence of PLL noise and obtaining a spectral purity of output signal, the level of a comparison frequency signal doesn't exceed -85 dBc.