Fano interferometric phase detector based phase locked loop

A fano interferometric phase detector comprising:

• a dielectric core with a top surface and a bottom surface, wherein the top surface and the bottom surface are substantially parallel;
• a main transmission line on the top surface;
• a first quarter wavelength stub on the top surface electrically coupled to the main transmission line;
• a second quarter wavelength stub on the top surface electrically coupled to the main transmission line;
• a first port line on the top surface and coupled to the main transmission line and the first quarter wavelength stub;
• a second port line on the top surface and coupled to the main transmission line and the second quarter wavelength stub;
• and
• a ground plane on the bottom surface, wherein the dielectric core insulates the ground plane from the main transmission line, the first quarter wavelength stub, the second quarter wavelength stub, and the first and second port lines.

A phase locked loop comprising:

• a fano interferometric phase detector configured to receive an input signal and a feedback signal, wherein the fano interferometric phase detector outputs a phase error signal depending on a phase difference of the input signal and the feedback signal;
• a loop filter to receive the phase error signal from the fano interferometric phase detector, perform a filtering operation on the phase error signal, and produce a fine control value based on the phase difference between the input signal and the feedback signal;
• and
• a voltage controlled oscillator configured to receive the fine control value from the loop filter and produce a voltage control oscillator (VCO) output with its phase adjusted based on the fine control value, wherein the VCO output is served as a phase locked loop output, wherein the phase locked loop output is a feedback signal to be fed into the fano interferometric phase detector, and wherein the feedback signal is aligned with the input signal when the feedback signal and the input signal are in-phase and their frequencies are equal or close to each other within an acceptable tolerance limit.