Phase-locking of grid oscillators

In this paper, we report results of the first successful phase locking, to our knowledge, of a grid oscillator. A voltage controlled grid with a center frequency of 4.7 GHz and with 300 MHz electric tuning range was locked to a frequency synthesizer by way of a phase-locked loop (PLL). The loop was designed with 10 kHz bandwidth and employs three operational amplifiers. Phase noise was improved to match the specification of the synthesizer locking source.