Ultralow phase noise reference signal generating device for frequency synthesizer

The invention relates to an ultralow phase noise reference signal generating device for a frequency synthesizer. The reference signal generating device comprises a crystal oscillator, a first phase locked loop and a second phase locked loop which are in sequential connection. The first phase locked loop comprises a first phase discriminator, a first loop filter and a voltage-controlled crystal oscillator which are in sequential connection, wherein the voltage-controlled crystal oscillator is connected with a feedback input end of the first phase discriminator. The second phase locked loop comprises a second phase discriminator, a second loop filter and a voltage-controlled surface acoustic wave oscillator which are in sequential connection, wherein the voltage-controlled surface acoustic wave oscillator is connected with a feedback input end of the second phase discriminator. Phase noises of reference signals generated by the ultralow phase noise reference signal generating device are optimal values at different frequency deviation positions of each oscillator, and the reference signal at each frequency deviation position can acquire the optimal phase noise.