US 12,191,867 B1
In-situ phase noise compensation for phononic frequency combs
Randall L. Kubena, Malibu, CA (US); and Walter S. Wall, Malibu, CA (US)
Assigned to HRL LABORATORIES, LLC, Malibu, CA (US)
Filed by HRL Laboratories, LLC, Malibu, CA (US)
Filed on Jun. 13, 2023, as Appl. No. 18/208,894.
Claims priority of provisional application 63/404,851, filed on Sep. 8, 2022.
Int. Cl. H03L 7/093 (2006.01); H03L 7/099 (2006.01)
CPC H03L 7/093 (2013.01) [H03L 7/0991 (2013.01)] 27 Claims
OG exemplary drawing
 
1. A phononic frequency comb enhanced clock, comprising:
a nonlinear resonator configured to generate a phononic frequency comb in response to a drive signal; and
an amplitude modulation (AM) to phase modulation (PM) noise correction circuit, comprising:
a transfer function circuit comprising:
a two-channel phase lock loop (PLL) with one channel input from the phononic frequency comb and another channel input from at least a portion of the drive signal; and
a digital signal processor (DSP) configured to divide a PM noise of a predetermined tooth (mth tooth) of the phononic frequency comb by an AM noise of the portion of the drive signal to generate a noise correction signal, wherein the predetermined tooth has higher AM/PM noise conversion compared to other teeth of the frequency comb, calculate filter coefficients for a digital filter function; and
a phase shifter having an input coupled to an output of the digital signal processor and another input connected to a frequency signal of a preselected tooth (nth tooth) of the frequency comb, wherein the preselected tooth is least sensitive to frequency changes of the drive signal compared to other teeth of the frequency comb.