A novel multistage sub-harmonic frequency-mixing phase locked loop(PLL) is provided to im-prove frequency synthesizer's spectral purity.Based on this method,an ultra- low phase noise frequency synthesizer is developed.The design of the frequency synthesizer is introduced and key technologies are an-alyzed.The main performance such as phase noise and spurious suppression is simulated and demonstra-ted.Finally,the C-band frequency synthesizer is measured.The synthesizer covers frequency from 4 500 MHz to 7 500 MHz with less 1 kHz step size.The measured phase noise at an output frequency of 7.49 GHz at 25 kHz offset is-123 dBc/Hz.Spurs do not exceed the 70 dB level and the switching time is less than 75 μs.The design scheme is more reasonable and feasible.With a small step size,fast frequency switching speed,low phase noise and low spurious characteristics,the synthesizer can be used in high per-formance electronic warfare receivers and has a broad application prospect.
电子战接收机 宽带频率合成器 C频段 多级子谐波混频 高纯度