Design of Fast Locking and Locking Detection System of Frequency Synthesizer

Abstract

In some electronic reconnaissance fields, fast frequency switching is required. A radio frequency signal generator with fast lock and accurate lock time appears to be of great significance. Traditional detection requires additional equipment, which is expensive and cumbersome to operate without portability. This paper designs a simple, portable and easy-to-operate lock detection method, uses a timer to monitor the LD pin of the phase lock chip in real time, optimizes the algorithm for capturing signal edge transitions, and calculates the frequency switching time. The ADF4351 fast lock mode is combined with lock detection to improve the topology of the loop filter and speed up the lock time. With the keyboard and LCD module, a radio frequency signal source system capable of self-checking and locking time is constructed. Simulation and actual results verify that after changing the filter structure to achieve quick lock, the lock time is optimized by 16%, which verifies the effectiveness of quick lock and the accuracy of lock detection, and realizes efficient and convenient lock time detection.