A wide frequency coverage synthesizer with high performance for 3MHz–5GHz transceiver

In this paper, an approach of developing high frequency resolution 3MHz-5GHz frequency synthesizer for a multi-channel wide band transceiver system is proposed. Using DDS (direct digital synthesizer) driven PLL (phase locked loop) structure to provide the local oscillators signal in a wide frequency range, with high-speed controlling of DSP (Digital Signal Processor), the frequency synthesizer implemented in the paper has good performance on spectrum purity. The minimum frequency resolution is 5Hz. The phase noise level is less than -80dBc/Hz@1kHz. The in-band and outside-band spurious level are below -55dBc and -65dBc accordingly. In frequency hopping mode, the frequency switching time is less than 30us.