Clock generation circuit

Patent metadata

Field	Value
Publication number	US-12050484-B2
Application number	US-201917051637-A
Country	US
Kind code	B2
Filing date	Apr 17, 2019
Priority date	May 1, 2018
Publication date	Jul 30, 2024
Grant date	Jul 30, 2024

Abstract

A clock generation circuit includes a mode-locked laser that generates an optical pulse, a photodiode that photoelectrically converts the optical pulse generated by the mode-locked laser, and a filter that attenuates at least one of a DC component and a harmonic component of the mode-locked laser included in an electric signal output from the photodiode.

First claim

The invention claimed is:

1. A clock generation circuit comprising:
a mode-locked laser that generates an optical pulse;
a photodetector that photoelectrically converts the optical pulse generated by the mode-locked laser into an electric clock signal, wherein the electric clock signal comprises a DC component and a harmonic component;
an amplifier that amplifies the electric clock signal output from the photodetector to reduce jitter in the electric clock signal, wherein a first cutoff frequency on a lower band side of the amplifier is higher than a frequency of the DC component of the electric clock signal output from the photodetector, and wherein a second cutoff frequency on a higher band side of the amplifier is lower than a frequency of the harmonic component of the electric clock signal output from the photodetector;
a first matching circuit between an output terminal of the photodetector and an input terminal of the amplifier, wherein the first matching circuit matches an impedance of the photodetector and the amplifier at a repetition frequency of the mode-locked laser;
a second matching circuit between an output terminal of the amplifier and an input terminal of a subsequent circuit connected to the amplifier, wherein the second matching circuit matches an impedance of the amplifier and the subsequent circuit at the repetition frequency of the mode-locked laser, wherein each of the first matching circuit and second matching circuits includes:
a first series resonator comprising a first series circuit composed of a first inductor and a first capacitor connected series in a signal line, wherein the first series resonator has a resonance frequency set to the repetition frequency of the mode-locked laser;
a second series resonator comprising a second series circuit composed of a second inductor and a second capacitor between the signal line and a negative power supply line, wherein the second series resonator has a resonance frequency set to the frequency of the harmonic component of the mode-locked laser;
a first parallel resonator comprising a first parallel circuit composed of a third inductor connected in series in the signal line and a third capacitor connected in parallel with the third inductor, wherein the first parallel resonator has a resonance frequency set to the frequency of the DC component or the frequency of the harmonic component of the mode-locked laser; or
a second parallel resonator comprising a second parallel circuit composed of a fourth inductor between the signal line and the negative power supply line and a fourth capacitor connected in parallel with the fourth inductor, wherein the second parallel resonator has a resonance frequency set to the repetition frequency of the mode-locked laser.

2. The clock generation circuit according to claim 1 , wherein the amplifier includes a frequency peaking circuit having a center frequency set to the repetition frequency of the mode-locked laser.

3. A clock generation circuit comprising:
a mode-locked laser that generates an optical pulse;
a photodetector that photoelectrically converts the optical pulse generated by the mode-locked laser into an electric clock signal, wherein the electric clock signal comprises a DC component and a harmonic component;
an amplifier that amplifies the electric clock signal output from the photodetector to reduce jitter in the electric clock signal, wherein a first cutoff frequency on a lower band side of the amplifier is higher than a frequency of the DC component of the electric clock signal output from the photodetector, and wherein a second cutoff frequency on a higher band side of the amplifier is lower than a frequency of the harmonic component of the electric clock signal output from the photodetector;
a first matching circuit between an output terminal of the photodetector and an input terminal of the amplifier, wherein the first matching circuit matches an impedance of the photodetector and the amplifier at a repetition frequency of the mode-locked laser;
a second matching circuit between an output terminal of the amplifier and an input terminal of a subsequent circuit connected to the amplifier, wherein the second matching circuit matches an impedance of the amplifier and the subsequent circuit at the repetition frequency of the mode-locked laser, wherein the amplifier comprises:
a first parallel resonator comprising a first parallel circuit composed of a first inductor between a positive power supply line and an input signal line and a first capacitor connected in parallel with the first inductor, wherein the first parallel resonator has a resonance frequency set to the repetition frequency of the mode-locked laser;
a second parallel resonator comprising a second parallel circuit composed of a second inductor between the positive power supply line and a positive power supply terminal of the amplifier and a second capacitor connected in parallel with the second inductor, wherein the second parallel resonator has a resonance frequency set to the frequency of the harmonic component of the mode-locked laser; or
a third parallel resonator comprising a third parallel circuit composed of a third inductor between a negative power supply terminal of the amplifier and a negative power supply line and a third capacitor connected in parallel with the third inductor, wherein the third parallel resonator has a resonance frequency set to the frequency of the harmonic component of the mode-locked laser.

4. The clock generation circuit according to claim 3 , wherein each of the first matching circuit and second matching circuits includes:
a first resonator comprising a first laminated inductor, wherein the first resonator has a resonance frequency set to the frequency of the DC component or the frequency of the harmonic component of the mode-locked laser; or
a second resonator comprising a second laminated inductor, wherein the second resonator has a resonance frequency set to the repetition frequency of the mode-locked laser.

5. A clock generation circuit comprising:
a mode-locked laser that generates an optical pulse;
a photodetector that photoelectrically converts the optical pulse generated by the mode-locked laser into an electric clock signal, wherein the electric clock signal comprises a DC component and a harmonic component;
an amplifier that amplifies the electric clock signal output from the photodetector to reduce jitter in the electric clock signal, wherein a first cutoff frequency on a lower band side of the amplifier is higher than a frequency of the DC component of the electric clock signal output from the photodetector, and wherein a second cutoff frequency on a higher band side of the amplifier is lower than a frequency of the harmonic component of the electric clock signal output from the photodetector;
a first matching circuit between an output terminal of the photodetector and an input terminal of the amplifier, wherein the first matching circuit matches an impedance of the photodetector and the amplifier at a repetition frequency of the mode-locked laser;
a second matching circuit between an output terminal of the amplifier and an input terminal of a subsequent circuit connected to the amplifier, wherein the second matching circuit matches an impedance of the amplifier and the subsequent circuit at the repetition frequency of the mode-locked laser, wherein the amplifier comprises:
a first resonator comprising a first laminated inductor, wherein the first resonator has a resonance frequency set to the repetition frequency of the mode-locked laser;
a second resonator comprising a second laminated inductor, wherein the second resonator has a resonance frequency set to the frequency of the harmonic component of the mode-locked laser; or
a third resonator comprising a third laminated indu

Assignees

• Nippon Telegraph & Telephone

Inventors

• Tanaka Kenji
• Miura Naoki
• Nakano Shinsuke
• Nosaka Hideyuki

Classifications

• H03F3/082

  with FET's (H03F3/085 takes precedence) · CPC title

• H03F1/223 Primary

  with MOSFET's · CPC title

• H03K3/42

  by the use, as active elements, of opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled · CPC title

• H03F3/08

  controlled by light · CPC title

• G06F1/06

  Clock generators producing several clock signals {(G06F1/08 - G06F1/14 take precedence)} · CPC title