Frequency synthesizer in the 55-65 GHz band for working with high-quality resonators

An inexpensive, high-precision synthesizer with a low level of phase noise was experimentally developed and implemented in the frequency range of 55-65 GHz at a power of 3 mW. The line width was less than 1 Hz, which depends on the line width of the reference frequency generator. Since the frequency of the backward wave oscillator is controlled by changing the input voltage, frequency stabilization has been achieved by using phase locked loop. Stability is determined by the reference oscillator and ranges from 1Hz (Short-term stability) to 100Hz (Long-term stability). А low division ratio is required to reduce phase noise, so a sub-harmonic mixer was used to down-convert the high frequency to a low intermediate frequency. The results obtained open up the possibility of measuring the properties of small materials using open resonators and make it possible to create a high-precision stable generator with a low level of phase noise in the terahertz range.