Direct Digital Synthesizer With Frequency Correction

A frequency synthesizer, comprising:

• a first clock source for providing a first fixed frequency clock signal having a first frequency;
• a second clock source for providing a second fixed frequency clock signal having a second frequency that is lower than the first frequency;
• a direct digital synthesizer configured to correct fora frequency error and/or a frequency wander of the first clock source using the second clock source and a frequency control word;
• and
• wherein the direct digital synthesizer comprises:
• a frequency correction circuit having a first input to receive the first fixed frequency clock signal, a second input to receive the second fixed frequency clock signal, and a third input to receive the frequency control word, and an output to provide a frequency error of the first fixed frequency clock signal, the frequency error determined using the second fixed frequency clock signal and the frequency control word.

An integrated circuit, comprising:

• a first input to receive a first fixed frequency clock signal having a first frequency between 1 GHz and 300 GHz;
• a second input to receive a second fixed frequency clock signal having a second frequency that is between 1 MHz and 500 MHz;
• and
• an output to provide an output frequency, the output frequency based at least in part on a frequency control word;
• wherein at least one of the first and second fixed frequency clock signals is a photonic signal.