A Fast Frequency Synthesizer for Microwave Radio

The exact system equations of the sampled PLL's using one or two sample-and-hold circuits are given. The model takes into account the characteristics of the realizable sampler circuits. By formulating the system equations as a fixed-point problem the behaviour of the loops is studied rigorously correctly from mathematical point of view, too. The conditions of the minimum acquisition time are determinated. Based on the theoretical results, an 8 GHz frequency synthesizer has been built. The measured frequency switching time is less than l0μs.