# US 12,113,540 B2 · Optical time synchronization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,113,540 B2 - Document ID: US12113540B2 - Status: Granted - Kind: B2 - Application number: 17/980,663 - Filed: 2022-11-04 - Published: 2023-05-11 - Granted: 2024-10-08 - Earliest claimed: 2021-11-05 - Assignees: DENSO International America, Inc. - Applicants: DENSO International America, Inc. - Inventors: Daniel Lee - Web page: https://patentgrep.com/patent/US12113540B2 ## CPC - G06F 1/04: Generating or distributing clock signals or signals derived directly therefrom - H03L 7/099: concerning mainly the controlled oscillator of the loop - G06F 1/06: Clock generators producing several clock signals {(G06F1/08 - G06F1/14 take precedence)} - G06F 1/105: {in which the distribution is at least partially optical} - G06F 1/12: Synchronisation of different clock signals {provided by a plurality of clock generators} - H03K 4/94: having trapezoidal shape - H03L 7/00: Automatic control of frequency or phase; Synchronisation - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) ## Abstract A system and method for synchronizing clocks. The system may include a master device having a reference clock and slave devices whose clocks may be synchronized with the reference clock. The master device may drive a light transmitter (e.g., LED) to produce a light pulse with each clock cycle of the reference clock. The light pluses may be distributed by a transmissive medium, such as a low cost optical fiber. ## Claims ### Claim 1 A system for generating a clock signal in a device, the system comprising: an optical receiver configured to receive light energy corresponding to a reference oscillation signal, the optical receiver operable to generate a receiver output based on the light energy; and an oscillator configured to generate an oscillating signal, the oscillator being operably coupled to the receiver output of the optical receiver, wherein the oscillating signal of the oscillator is substantially locked to the reference oscillation signal received via the optical receiver, wherein the oscillator is a crystal oscillator. ### Claim 2 (depends on 1) The system of claim 1 comprising an amplifier operably coupled to the oscillator, the amplifier configured to generate the clock signal based on the oscillating signal generated by the oscillator. ### Claim 3 (depends on 2) The system of claim 2 wherein the amplifier includes a first amplifier stage directly connected to the oscillator and configured to generate a first amplifier output based on the oscillating signal, and wherein the amplifier includes a second amplifier stage coupled to the first amplifier stage and configured to generate a second amplifier output based on the first amplifier output such that the second amplifier output is based on the oscillating signal. ### Claim 4 (depends on 2) The system of claim 2 wherein the oscillator and the amplifier form a superregenerative receiver with respect to the receiver output that is based on the reference oscillation signal. ### Claim 5 (depends on 1) The system of claim 1 wherein a mechanical vibration of the crystal oscillator is varied based on the receiver output such that the mechanical vibration of the crystal oscillator is locked to the reference oscillation signal. ### Claim 6 (depends on 1) The system of claim 1 comprising: a reference oscillator operable to generate the reference oscillation signal; an optical transmitter operably coupled to the reference oscillator, the optical transmitter arranged to generate the light energy corresponding to the reference oscillation signal; wherein the optical receiver and the oscillator are disposed in the device; and wherein the reference oscillator and the optical transmitter are disposed in a remote device that is remote from the device, the optical receiver, and the oscillator. ### Claim 7 (depends on 6) The system of claim 6 comprising a fiber medium operably coupled between the optical transmitter and the optical receiver. ### Claim 8 (depends on 6) The system of claim 6 wherein the oscillating signal of the oscillator is substantially locked to the reference oscillation signal in an open loop manner such that the reference oscillator is unaffected by operation of the oscillator. ### Claim 9 (depends on 1) The system of claim 1 comprising a slave device including the optical receiver and the oscillator, and wherein the system includes a plurality of such slave devices each capable of locking with the reference oscillation signal. ### Claim 10 A slave device that is remote from a master device, the slave device comprising: an optical receiver configured to receive light energy corresponding to a reference oscillation signal generated by the master device, the optical receiver operable to generate a receiver output based on the light energy; and an oscillator configured to generate an oscillating signal, the oscillator being operably coupled to the receiver output of the optical receiver, wherein the oscillating signal of the oscillator is substantially locked to the reference oscillation signal received via the optical receiver and generated remotely from the optical receiver, wherein the oscillator is a crystal oscillator. ### Claim 11 (depends on 10) The slave device of claim 10 comprising an amplifier operably coupled to the oscillator, the amplifier configured to generate a clock signal based on the oscillating signal generated by the oscillator. ### Claim 12 (depends on 11) The slave device of claim 11 wherein the amplifier includes a first amplifier stage directly connected to the oscillator and configured to generate a first amplifier output based on the oscillating signal, and wherein the amplifier includes a second amplifier stage coupled to the first amplifier stage and configured to generate a second amplifier output based on the first amplifier output such that the second amplifier output is based on the oscillating signal. ### Claim 13 (depends on 11) The slave device of claim 11 wherein the oscillator and the amplifier form a superregenerative receiver with respect to the receiver output that is based on the reference oscillation signal. ### Claim 14 (depends on 10) The slave device of claim 10 wherein a mechanical vibration of the crystal oscillator is varied based on the receiver output such that the mechanical vibration of the crystal oscillator is locked to the reference oscillation signal. ### Claim 15 (depends on 10) The slave device of claim 10 wherein the optical receiver is operably coupled to a fiber medium to receive the light energy transmitted by the master device. ### Claim 16 (depends on 10) The slave device of claim 10 wherein the oscillating signal of the oscillator is substantially locked to the reference oscillation signal in an open loop manner such that the reference oscillation signal is unaffected by operation of the oscillator. ### Claim 17 A method of synchronizing an oscillation signal to a reference oscillation signal that is generated remotely from the oscillation signal, the method comprising: receiving light energy corresponding to the reference oscillation signal; generating a receiver output based on the light energy; and substantially locking an oscillator signal to the reference oscillation signal; and generating the oscillator signal via a crystal oscillator. ### Claim 18 (depends on 17) The method of claim 17 comprising amplifying the oscillator signal to yield a clock signal.