A new small-dimensions full PLL system

During last years super low-noise high-frequency oscillators have got more and more applications in a number of new systems. This kind of HF OCXO usually has low temperature and long-term stability. Higher stability may be achieved in a phase locked loop system (PLL) using a low-frequency precision oscillator as a reference. Such a system usually has big size and high power consumption. One of the ways to solve this problem is to use a combined oven for both of OCXO. But then some problems because of different temperature level and stability required for both OCXO have appeared. One more problem is to save the low noise floor of HF OCXO in close presence of another OCXO. During the last year the design of such a small size full PLL system including both OCXO was made using a special calculation to minimize temperature gradients in a reference crystal in the presence of high-frequency crystal. The optimized topology in a planar-designed system allows the saving of the noise floor of HF OCXO. The achieved main parameters of the PLL-OCXO model described above are: frequency 100 MHz; noise floor -165...-170 dBc; frequency stability versus temperature range -40...+70°C ±5·10^-10; long-term stability ±5·10^-8/year; power consumption (steady state) <2.5 W; dimensions 50.8·50.8·16 mm.