Design of a Low Phase Noise Frequency Source Based on PLL Technology in C-Band

This work designs and implements a low phase noise C-band frequency source based on Phase-Locked Loop (PLL) technology, operating in the 6.5-8.0 GHz band. The system adopts a programmable microcontroller to dynamically configure the division ratio and operating modes of the LMX2492 phase-frequency discriminator (PFD) via the SPI interface. Combined with the HMC508 voltage-controlled oscillator (VCO) with a half-frequency output function and Rogers RO4350B high-frequency PCB substrate, flexible frequency control is achieved. Experimental results show that the average frequency error across four test points is better than ±1×10^-5, with output power levels exceeding 6 dBm and phase noise at 6.6 GHz is - 90.54@lkHz, -99.10@10kHz, etc. This design meets the requirements of phased-array radars, satellite communications, and other fields for high-performance C-band signals, providing reliable frequency support.