Abstract: To satisfy the PCM telemetry baseband equipment performance requirements of the ground system of Beijing TTC&M earth station, a new design technique of digitized synthesizer whose output frequency can be changed continuously(resolution:1Hz)is proposed in this paper.The mathod of improving the output signal frequency resolution and stability using PLL technique are mainly described.The idea of"swallow pulse" progranlable dividing frequency and its circuit composition are discussed in detail.The design diagram of PLL is also provided.