Abstract: In the field of broadband electromagnetic receivers, high-frequency frequency sources usually have problems such as low output power and poor phase noise performance, so frequency source performance is particularly important. To address this problem, this paper uses phase-locked loop and frequency multiplication design methods to design a miniaturized K-band frequency source. First, the phase-locked loop circuit, control unit circuit and voltage-stabilized power supply circuit are designed, and then the frequency source is modeled and simulated to verify its feasibility. The phase-locked loop circuit and control unit are completed by using cavity design and micro-assembly, the design of the voltage-stabilized power supply circuit and the frequency multiplier, and finally the frequency source was tested. The test results show that the output frequency of this frequency source is 25. 6 GHz, the output power is greater than 10 dBm, its normalized phase noise is-76 dBc/Hz@100 kHz, and its overall size is 60 mm×40 mm×8 mm. The designed frequency source has the advantages of small size, excellent performance and longterm stable operation, and it can meet the application requirements of broadband receiver engineering.