Development of an anti-vibration crystal oscillator for reducing vibration-induced phase noise

Crystal oscillators are acceleration sensitive devices. Vibration will degrade the phase noise of crystal oscillators in many applications such as aircrafts, ground vehicles, and even in the laboratory due to cooling fans, footsteps, etc. This paper presents development of an anti-vibration crystal oscillator (AVXO) for reducing phase noise degradation due to mechanical vibration on the crystal oscillator. The approach for reducing phase noise degradation starts with choosing crystal resonators, designing isolators, and simulating the transmissibility of the isolator and the phase noise of the AVXO under random vibration. The measured phase noise is typically better than -145dBc/Hz at 1 kHz offset frequency from the carrier frequency of 100 MHz, when crystal oscillators are under operational vibration condition. The measured results show that the isolator in the AVXO is actually providing in excess of 40 dB improvement at 1 kHz offset frequency.