Design and implementation of a fractional-N frequency source

A transmitter local oscillator based on the fractional-N PLL chip ADF4193 is designed in this paper, the local oscillator achieve a relatively small frequency step in the case of selecting high phase detector frequency, thus optimized the system phase noise, and effectively meet the application requirements of Unmanned Aerial Vehicle (UAV) data link frequency source. Compared with traditional integer-N divider system, the actual testing and application results show that the phase noise of the local oscillator reduced 10dB, and the system has short lock time, low spurious, good practical value.