Ultralow phase noise Crystal Oscillators and Atomic Clocks

Reference oscillators and clocks are essential elements in almost all electronic systems and consumer and professional products as the phase noise, jitter and stability of these oscillators usually sets the ultimate performance limit.
High performance oscillators, exhibiting low phase noise, are required in communications, control, RADAR & navigation systems & also as flywheel oscillators for atomic clocks, optical clocks, accelerator & Very Long Base Interferometry (VLBI) systems.
The aim of this research is to develop new ultralow phase noise compact crystal oscillators with improved short and long term stability with phase noise (at 100 MHz) significantly below -140dBc at 100 Hz offset, low noise floors and for 5 and 10MHz oscillators phase noise below -130dBc at 1Hz (5MHz) and -123dBc at 1Hz (10MHz) and ADEV (5 and 10MHz) below 10-13 from 0.1 sec to many hundreds of seconds. The aim is to develop new amplifiers which offer low noise figure, ultralow residual flicker noise, accurate limiting and control of resonator power and excellent temperature stability. An additional key feature is to improve the longer-term frequency stability by developing new highly stable temperature control loops with more accurate control of heat flow and accurate setting of the turnover temperature of the crystal resonator. Low phase noise electronic frequency tuning will be investigated.
These oscillators will then be used in atomic clocks to improve both the short and long term frequency stability.
Companies and research organization involved with this research work at York include: Keysight, Teledyne-e2V, Leonardo, Daresbury Research Laboratories and NPL.