Ovenized crystal oscillator reference frequency signal generator

A system, comprising:

• a first ovenized reference crystal oscillator (OCXO) having a first input and a first output;
• a second OCXO having a second input and a second output;
• a third OCXO having a third input and a third output;
• a first logic circuit having a first logic input coupled to the first output, a second logic input coupled to the second output, a first control input, and a first logic output;
• a second logic circuit having a third logic input coupled to the second output, a fourth logic input coupled to the third output, a second control input, and a second logic output;
• a first phase-locked loop (PLL) having a first PLL input coupled to the first logic output, a second PLL input, and a first PLL output;
• a second PLL having a third PLL input coupled to the second logic output, a fourth PLL input, and a second PLL output;
• a third logic circuit having a fifth logic input coupled to the first PLL output, a sixth logic input coupled to the second PLL output, a third control input, and a third logic output;
• a third PLL having a fifth PLL input coupled to the first PLL output, a sixth PLL input coupled to the second PLL output, a communications bus, and a third PLL output coupled to the fourth PLL input;
• a temperature sensor having a temperature sensor output;
• and
• a controller coupled to the communications bus, the controller having:
• a first input coupled to the temperature sensor output,
• a first output coupled to the first, second, and third inputs,
• a second output coupled to the first control input,
• a third output coupled to the second control input,
• a fourth output coupled to the second PLL input, and
• a fifth output coupled to the third control input.

A device, comprising:

• a first and a second ovenized reference crystal oscillator (OCXO), the first and second OCXOs having different turn-over-temperatures (TOTs);
• a selector logic circuit coupled to the first and second OCXOs and configured to output a particular OCXO output based on a control signal;
• a temperature sensor configured to measure an environmental temperature of the device;
• and
• a controller configured to:
• receive the environmental temperature from the temperature sensor;
• determine the environmental temperature is within an operating temperature range of a particular OCXO of the first and the second OCXO based on the respective TOT;
• cause the particular OCXO to generate the particular OCXO output;
• and
• generate the control signal to cause the selector logic circuit to output the particular OCXO output.