只好用频率计测试，无外部参考时，频率计参考内部时钟（OCXO），精度在1到3PPM左右 我公司招聘晶振研发人员有意请与我联系：dean.liang@temex.com     Engineer in Electronics (analogical or RF or Microwave), 3 to 5 years experience in oscillators development (XO ,VCXO, TCXO, OCXO or VCO) Key background :     -          oscillators with crystal resonator     -          optimization of the phase noise     -          oscillators aging     -          amplifier, circuits to generate sinus, square signal     -          Thermal regulation + different way to control the temperature in an oven In addition,        - Knowledge of  crystal resonators         - Experience on simulation tools (ADS, Spice, .)         - Experience of high performances oscillators design by using "platform" with design rules         will be highly appreciated Cost minded , good communication, able to cooperate with different teams (production, industrialization, ..) English : (read, write & speaking) Must be available for training sessions :several sessions  2 to 3 weeks each (in France)