DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Information Disclosure Statement
The information disclosure statement (IDS) submitted on 4/27/2023 is being considered by the examiner.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-4, 9 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Rideout et al (Rideout et al: “Discriminator-Aided Optical Phase-Lock Loop Incorporating a Frequency Down-Conversion Module”, IEEE Photonics Technology Letters, November 15, 2006, Vol. 8, No. 22, pages 2344-2346) in view of Middleton et al (US 2013/0177319) and Ryu et al (US 4,888,817) and Mehrgardt (US 4,634,989).
1). With regard to claim 1, Rideout et al discloses an electronic device (Figure 1) comprising:
a signal source (e.g., the Master Laser in Figure 1);
a loop path (the loop path from the Master laser -> PD -> Down-conversion -> Splitter -> Frequency Discriminator -> Master laser) that couples an output of the signal source (the output of the Master laser) to an input of the signal source (the input that accepts the signal from the Frequency Discriminator); and
a frequency discriminator (the Frequency Discriminator in Figure 1) disposed on the loop path, the frequency discriminator including
a mixer (the Mixer M2) having an output communicably coupled to the input of the signal source,
a delay (the Delay Line) coupled between a splitter (the Splitter in the Frequency Discriminator) and the digital mixer (Mixer M2), and
a phase shifter coupled between the splitter and the mixer (it is common that either the mixer or the splitter would introduce a phase shift).
But, Rideout et al does not expressly disclose that the signal source generate a clock signal, and the frequency discriminator is a digital frequency discriminator including a converter having an input communicably coupled to the output of the signal source, a digital mixer having an output communicably coupled to the input of the signal source, a digital delay coupled between the converter and the digital mixer, and a digital phase shifter coupled between the converter and the digital mixer in parallel with the digital delay.
Regarding generating a clock signal, however, first, Rideout et al discloses that the system shown in Figure 1 can be used for radio-over-fiber (RoF) (page 2344, I. Introduction, and II. Design and Analysis), and the Down-conversion circuit (the combination of Photodetector, Amp 1 and Down-conversion module in Figure 1) down-converts the optical signal (Rideout: page 2344, II. Design And Analysis, “In this new configuration, to generate a microwave signal at 11.2 GHz, S1 is chosen to operate at 12 GHz, so that the frequency discriminator now operates at the offset frequency of these two, which is 800 MHz. The discriminator, a two-tap delay line filter, is designed by controlling the delay line length such that is has an operating null at 800 MHz. A DC feedback proportional to the difference between the down-converted frequency and the 800-MHz null is generated and sent to the master laser to maintain a fixed wavelength difference corresponding to 11.2 GHz”). Following Figure O1 is a comparison between Applicant’s Figure 12 (claimed features) and Figure 1 of Rideout.
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Figure O1 (Comparison)
As shown in Figure O1 above (comparison), Applicant discloses two lasers (primary laser and secondary laser), and Rideout et al also discloses two lasers (Master laser and Slave laser); Applicant discloses a feedback control loop path, and Rideout et al also discloses a feedback control loop path; Applicant discloses a Down-conversion circuitry, and Rideout et al also discloses a Down-conversion circuitry; Applicant discloses a Phase Detector, and Rideout et al also discloses a Phase Detector. The only different is that Applicant uses a digital frequency discriminator (DFD), but Rideout et al uses a Frequency Discriminator (may not a digital frequency discriminator). Therefore, it is obvious to one skilled in the art that the system/method disclosed by Rideout can be used to control/stabilize a laser source that generates a clock signal.
Second, to use a laser to generate a clock signal or local oscillator signal is well known in the art. E.g., Middleton et al discloses a wireless communication system/method with optical carriers et al (Figures 2 and 4), in which a laser (28 in Figure 2; or a set of CW laser 62) generates a clock signal (modulated by the local oscillator 32 via the modulator 30), “a modulated optical carrier signal commensurate of the LO frequency” ([0028]). Also, another prior art, Ryu et al, discloses a system/method (Figure 3) in which a frequency discriminator (10) is used to control the frequency of the local oscillator laser (2) (column 3 lines 29-68). Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teaching of Middleton et al and Ryu et al to the system/method of Rideout et al so that the system as disclosed by Rideout et al can be used to control the frequency of local oscillator having a clock signal.
Regarding a digital frequency discriminator, a digital frequency discriminator is well known in the art and commercially available. E.g., Mehrgardt discloses a digital frequency discriminator (Figure 1 etc.) including
a converter (A/D converter “aw” in Figure 1) having an input (the input that accepts the signal “a1”) communicably coupled to the output of a signal source (the signal source that generates the “a1” signal),
a digital mixer (the Adder “ad”) having an output communicably coupled to the input of the signal source (Figure 1),
a digital delay (e.g., Delay “v1” etc.) coupled between the converter and the digital mixer, and
a digital phase shifter (e.g., Phase shifter “ht”) coupled between the converter and the digital mixer in parallel with the digital delay (Figure 1).
A digital frequency discriminator has the advantage of greater accuracy, flexibility, and noise immunity, along with benefits like easier integration into complex system. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to combine Mehrgardt with Rideout et al and Middleton et al and Ryu et al so that a digital frequency discriminator is used for controlling the clock signal or local oscillator more accurately.
2). With regard to claim 2, Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claim 1 above. And the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt further discloses
wherein the converter is configured to convert the clock signal into a digital signal, the digital delay is configured to generate a delayed signal by applying a time delay to the digital signal (Rideout and Mehrgardt: a time delay is applied to one path), the digital phase shifter is configured to generate a phase shifted signal by applying a phase shift to the digital signal (Rideout and Mehrgardt: phase delay is applied to another path), and the mixer is configured to generate a control signal by mixing the phase shifted signal with the delayed signal (Rideout: Mixer M2; and Mehrgardt: adder “ad”).
3). With regard to claim 3, Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claims 1 and 2 above. And the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt further discloses
wherein the phase shift is a 90-degree phase shift (Mehrgardt: digital 90o phase shifter ht, column 2 lines 27-31)
4). With regard to claim 4, Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claims 1 and 2 above. And the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt further discloses
wherein the signal source is configured to adjust the clock signal based on the control signal (Rideout: feedback control signal from the Frequency Discriminator is input to the Master Laser. Ryu: Figure 3, the control circuit 11 receives signals from the frequency discriminator 10 and then control the laser local oscillator 2).
5). With regard to claim 9, Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claim 1 above. And the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt further discloses
wherein the converter comprises an analog-to-digital converter (ADC) (e.g., Mehrgardt: A/D “aw”).
6). With regard to claim 12, Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claim 1 above. And the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt further discloses
wherein the digital delay comprises a set of delay stages coupled in series between the converter and the digital mixer (e.g., Mehrgardt: Figure 1, the delay element “v1” and the delay element “v2” coupled in series between the converter “A/D aw” and the digital mixer “ADDER ad”).
Claims 5-6 and 10 are rejected under 35 U.S.C. 103 as being unpatentable over Rideout et al and Middleton et al and Ryu et al and Mehrgardt as applied to claims 1-2 above, and further in view of Noguchi (US 2025/0167893) and Relph (US 6,218,880).
1). With regard to claim 5, Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claims 1-2 above. But, Rideout et al and Middleton et al and Ryu et al and Mehrgardt do not expressly disclose the electronic device of claim 2, the frequency discriminator further comprising: an additional converter coupled between an output of the digital mixer and the input of the signal source, wherein the additional converter is configured to convert the control signal from a digital domain to an analog domain.
However, as discussed in claims 1-2 rejection, the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt discloses a digital frequency discriminator; and Mehrgardt discloses that an analog-to-digital converter (A/D) is used before the digital delay and digital phase shifter. In Figure 1 of Rideout, the control signal sent from the Frequency Discriminator to the Master Laser is an analog signal, therefore, it is obvious to one skilled in the art that a digital-to-analog converter is needed after the digital mixer (e.g., the adder “ad” of Mehrgardt) so to convert a digital signal back to the analog signal to control the laser. Noguchi discloses a procedure to process a signal in digital domain (Figure 14), in which an analog signal (SA1) is first converted into digital signal (SD1) and then the digital signal is processed by a digital signal processing unit (230), and then processed digital signal (SD2) is converted into an analog signal (SA2) by a DAC (270), and then to a front-end unit (220). Relph discloses a digital delay line (Figure 2), in which an analog signal (ANALOG IN) is first converted into digital signal by an A/D converter 202 and then the digital signal pass through multiple digital delay lines 100-170, and then a digital to analog converter 204 converts the delayed digital signals into an analog signal (ANALOG OUT).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply a D/A converter as taught by Noguchi and Relph to the system/method of Rideout et al and Middleton et al and Ryu et al and Mehrgardt so that the digital signal is converted back to analog signal to control the signal source (master laser).
2). With regard to claim 6, Rideout et al and Middleton et al and Ryu et al and Mehrgardt and Noguchi and Relph disclose all of the subject matter as applied to claims 1-2 and 5 above. And the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt and Noguchi and Relph further discloses the electronic device of claim 5, the frequency discriminator further comprising:
a filter (e.g., Rideout: Low-pass filer LP1) coupled between an output of the additional converter and the input of the signal source.
3). With regard to claim 10, Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claim 1 above. But, Rideout et al and Middleton et al and Ryu et al and Mehrgardt do not expressly disclose the electronic device of claim 1, the frequency discriminator further comprising: a digital-to-analog converter (DAC) coupled between the output of the digital mixer and the input of the signal source.
However, as discussed in claim 1 rejection, the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt discloses a digital frequency discriminator; and Mehrgardt discloses that an analog-to-digital converter (A/D) is used before the digital delay and digital phase shifter. In Figure 1 of Rideout, the control signal sent from the Frequency Discriminator to the Master Laser is an analog signal, therefore, it is obvious to one skilled in the art that a digital-to-analog converter (DAC) is needed after the digital mixer (e.g., the adder “ad” of Mehrgardt) so to convert a digital signal back to the analog signal to control the laser. Noguchi discloses a procedure to process a signal in digital domain (Figure 14), in which an analog signal (SA1) is first converted into digital signal (SD1) and then the digital signal is processed by a digital signal processing unit (230), and then processed digital signal (SD2) is converted into an analog signal (SA2) by a DAC (270), and then to a front-end unit (220). Relph discloses a digital delay line (Figure 2), in which an analog signal (ANALOG IN) is first converted into digital signal by an A/D converter 202 and then the digital signal pass through multiple digital delay lines 100-170, and then a digital to analog converter (DAC) 204 converts the delayed digital signals into an analog signal (ANALOG OUT).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply a DAC converter as taught by Noguchi and Relph to the system/method of Rideout et al and Middleton et al and Ryu et al and Mehrgardt so that the digital signal is converted back to analog signal to control the signal source (master laser).
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Rideout et al and Middleton et al and Ryu et al and Mehrgardt as applied to claim 1 above, and further in view of Deng et al (US 9.979,405).
Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claim 1 above. But, Rideout et al and Middleton et al and Ryu et al and Mehrgardt do not expressly disclose wherein the converter comprises a time-to-digital converter (TDC).
However, a TDC is well known in the art to perform an analog to digital conversion. E.g., Deng et al discloses a phase lock loop (Figure 3 etc.) in which a TDC (202) is used to convert a clock signal (RefClk) to a digital signal, which is further processed by digital circuits (204/206/208 etc.).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the TDC as the converter as taught by Deng et al to the system/method of Rideout et al and Middleton et al and Ryu et al and Mehrgardt so that the clock signal can be precisely controlled, and timing is more reliable.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Rideout et al and Middleton et al and Ryu et al and Mehrgardt and Deng et al as applied to claims 1 and 7 above, and further in view of Relph (US 6,218,880).
Rideout et al and Middleton et al and Ryu et al and Mehrgardt and Deng e al disclose all of the subject matter as applied to claims 1 and 7 above. But, Rideout et al and Middleton et al and Ryu et al and Mehrgardt and Deng et al do not expressly disclose the electronic device of claim 7, the frequency discriminator further comprising: a digital-to-time converter (DTC) coupled between the output of the digital mixer and the input of the signal source.
However, as discussed in claim 1 rejection, the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt discloses a digital frequency discriminator; and Mehrgardt discloses that an analog-to-digital converter (A/D) is used before the digital delay and digital phase shifter. In Figure 1 of Rideout, the control signal sent from the Frequency Discriminator to the Master Laser is an analog signal, therefore, it is obvious to one skilled in the art that a digital-to-analog converter is needed after the digital mixer (e.g., the adder “ad” of Mehrgardt) so to convert a digital signal back to the analog signal to control the laser. Relph discloses a digital delay line (Figure 2), in which an analog signal (ANALOG IN) is first converted into digital signal by an A/D converter 202 and then the digital signal pass through multiple digital delay lines 100-170, and then a digital to analog converter 204 converts the delayed digital signals into an analog signal (ANALOG OUT).
Regarding use a digital-to-time converter (DTC) to convert the digital signal back to the analog signal, however, a DTC is well known in the art to perform digital to analog conversion. E.g., Deng et al discloses a phase lock loop (Figure 3 etc.) in which a TDC (202) is used to convert a clock signal (RefClk) to a digital signal, which is further processed by digital circuits (204/206/208 etc.), and then after the digital signal processing, a feedback signal is converted back to an analog signal by the DTC 217.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to combine Relph with Rideout et al and Middleton et al and Ryu et al and Mehrgardt and Deng et al so that a DTC is used between the output of the digital mixer and the input of the signal source to convert a digital signal to an analog signal so to obtain a proper control signal for the signal source (master laser).
Claim 11 is rejected under 35 U.S.C. 103 as being unpatentable over Rideout et al and Middleton et al and Ryu et al and Mehrgardt as applied to claim 1 above, and further in view of Relph (US 6,218,880).
Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claim 1 above. But, Rideout et al and Middleton et al and Ryu et al and Mehrgardt do not expressly disclose wherein the digital delay comprises a set of delay stages coupled in parallel between the converter and the digital mixer.
However, to use a digital delay having a set of delay stages in parallel is known in the art. E.g., Relph discloses a digital delay line (Figure 3) comprising a set of delay stages (100 to 179) coupled in parallel between a converter (ADC 202) and a digital mixer (the combiner before the DAC 204). Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Relph to the system/method of Rideout et al and Middleton et al and Ryu et al and Mehrgardt so that a more accurate time delay can be obtained.
Claims 13 and 14 are rejected under 35 U.S.C. 103 as being unpatentable over Rideout et al and Middleton et al and Ryu et al and Mehrgardt as applied to claim 1 above, and further in view of Kim et al (US 2022/0303017).
1). With regard to claim 13, Rideout et al and Middleton et al and Ryu et al and Mehrgardt disclose all of the subject matter as applied to claim 1 above. And the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt further discloses wherein the signal source comprises a laser (e.g., Master Laser in Figure 1 of Rideout. Middleton: Laser 28; and Ryu: Laser for local oscillator 2) and the clock signal is an optical local oscillator (LO) signal (refer claim 1 rejection. And Middleton: Laser 28 for local oscillator; and Ryu: Laser for local oscillator 2. And, Ryu et al teaches that a frequency discriminator (10) is used to control the frequency of the local oscillator laser; and Rideout also discloses system is used for radio-over-fiber (RoF), page 2344, I. Introduction, and II. Design and Analysis).
But, Rideout et al and Middleton et al and Ryu et al and Mehrgardt do not expressly disclose the electronic device further comprising: an antenna radiating element; and a photodiode configured to produce an antenna current on the antenna radiating element based on the optical LO signal.
First, as discussed above, Rideout also discloses that the system is used for radio-over-fiber (RoF), and Middleton et al discloses a wireless communication system/method with optical carriers et al (Figures 2 and 4); it is obvious to one skilled in the art that the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt can be used for radio-over-fiber hybrid wireless communications.
Second, Kim et al discloses a light-based wireless transmission system (Figure 1) comprising: an antenna radiating element (179), and a photodiode (160) configured to produce an antenna current on the antenna radiating element based on the optical LO signal (from local oscillator 110).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Kim et al to the system/method of Rideout et al and Middleton et al and Ryu et al and Mehrgardt so that the system/method can be used in a RoF wireless communication system and to obtain a frequency and phase stabilized local oscillator.
2). With regard to claim 14, Rideout et al and Middleton et al and Ryu et al and Mehrgardt and Kim et al disclose all of the subject matter as applied to claims 1 and 13 above. And the combination of Rideout et al and Middleton et al and Ryu et al and Mehrgardt and Kim et al further discloses the electronic device of claim 13, further comprising:
downconversion circuitry (e.g., Rideout: the combination of Photodetector, Amp 1 and Down-conversion module in Figure 1) disposed on the loop path between the frequency discriminator and the output of the signal source (Rideout: via a splitter that splits portion of optical signal to the Photodetector, Figure 1), the downconversion circuitry being configured to convert the optical LO signal into a radio-frequency signal (Rideout: page 2344, II. Design And Analysis, “In this new configuration, to generate a microwave signal at 11.2 GHz, S1 is chosen to operate at 12 GHz, so that the frequency discriminator now operates at the offset frequency of these two, which is 800 MHz. The discriminator, a two-tap delay line filter, is designed by controlling the delay line length such that is has an operating null at 800 MHz. A DC feedback proportional to the difference between the down-converted frequency and the 800-MHz null is generated and sent to the master laser to maintain a fixed wavelength difference corresponding to 11.2 GHz”).
Claims 15 and 17-18 are rejected under 35 U.S.C. 103 as being unpatentable over Mehrgardt (US 4,634,989) in view of Noguchi (US 2025/0167893) and Relph (US 6,218,880).
1). With regard to claim 15, Mehrgardt discloses a frequency discriminator (Figure 1 etc.) comprising:
an input converter (A/D converter “aw” in Figure 1);
a digital mixer (the Adder “ad”) having a first input coupled to an output of the input converter over a first path (the input for the signal over the upper path Delay v1 -> Delay v2 -> Mult m1 -> Adder) and having a second input coupled to the output of the input converter over a second path (the input for the signal over the bottom Phase shifter ht -> Delay v3 -> Mult m2 -> Adder) parallel to the first path (Figure 1);
a digital delay circuit (Delay v1 and Delay v2) disposed on the first path;
a digital phase shifter (Phase shifter ht) disposed on the second path.
But, Mehrgardt does not expressly disclose an output converter coupled to an output of the digital mixer. However, when the output signal from the digital frequency discriminator is used for control purpose and an analog signal is needed, it is obvious to one skilled in the art that an output converter, e.g., a Digital-to-Analog converter (DAC), is needed to be coupled to the output of the digital mixer so to obtain an analog signal. E.g., Noguchi discloses a procedure to process a signal in digital domain (Figure 14), in which an analog signal (SA1) is first converted into digital signal (SD1) and then the digital signal is processed by a digital signal processing unit (230), and then processed digital signal (SD2) is converted back to an analog signal (SA2) by a DAC (270), and then to a front-end unit (220). Another prior art, Relph discloses a digital delay line (Figure 2), in which an analog signal (ANALOG IN) is first converted to digital signal by an A/D converter 202 and then the digital signal pass through multiple digital delay lines 100-170, and then a digital to analog converter 204 converts the delayed digital signals into an analog signal (ANALOG OUT).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply a DAC as taught by Noguchi and Relph to the system of Mehrgardt so that the digital signal is converted back to an analog signal, and to use the analog signal for a desired purpose.
2). With regard to claim 17, Mehrgardt and Noguchi and Relph disclose all of the subject matter as applied to claim 15 above. And the combination of Mehrgardt and Noguchi and Relph further discloses
wherein the input converter comprises a time-to-digital converter (TDC) or an analog-to-digital converter (ADC) (Mehrgardt and Noguchi and Relph: ADC is used as the input converter).
2). With regard to claim 18, Mehrgardt and Noguchi and Relph disclose all of the subject matter as applied to claim 15 above. And the combination of Mehrgardt and Noguchi and Relph further discloses
wherein the output converter comprises a digital-to-time converter (DTC) or a digital-to-analog converter (DAC) (Mehrgardt and Noguchi and Relph: DAC is used as the output converter).
Claim 16 is rejected under 35 U.S.C. 103 as being unpatentable over Mehrgardt and Noguchi and Relph as applied to claim 15 above, and further in view of Rideout et al (Rideout et al: “Discriminator-Aided Optical Phase-Lock Loop Incorporating a Frequency Down-Conversion Module”, IEEE Photonics Technology Letters, November 15, 2006, Vol. 8, No. 22, pages 2344-2346) and Middleton et al (US 2013/0177319) and Ryu et al (US 4,888,817).
Mehrgardt and Noguchi and Relph disclose all of the subject matter as applied to claim 15 above. And the combination of Mehrgardt and Noguchi and Relph further discloses
wherein the input converter is configured to receive a signal (Mehrgardt: Figure 1, signal a1) and is configured to convert the signal into a digital signal (Mehrgardt: by the A/D converter: aw), the digital delay circuit (Mehrgardt: Delay v1 and delay v2) is configured to generate a delayed signal based on the digital signal, the digital phase shifter (Phase shifter ht) is configured to generate a phase shifted signal by applying a 90-degree phase shift (Mehrgardt: digital 90o phase shifter ht, column 2 lines 27-31) to the digital signal, and the output converter is configured to convert the digital signal, which is processed by the delay circuit and phase shift, from a digital domain to an analog domain (Relph: DAC output converter).
But, Mehrgardt and Noguchi and Relph do not expressly disclose that the signal received is a clock signal; and the mixer is configured to generate a control signal indicative of a phase noise of the clock signal by mixing the delayed signal with the phase shifted signal, and the output converter is configured to convert the control signal from a digital domain to an analog domain.
However, first, Rideout et al discloses a system/method in which a low phase noise, highly frequency-stable, and frequency-tunable radio frequency signal can be generated using a discriminator-aided optical phase-lock loop (OPLL) incorporating a frequency down-conversion module to generate (Figure 1). As shown in Figure 1, a mixer (Mixer M2) is configured to generate a control signal (the signal output from the Frequency Discriminator) indicative of a phase noise of a signal (originated from a Master Laser; page 2345, B. Phase Noise Analysis and III. Results etc.) by mixing the delayed signal (via a Delay Line) with the phase shifted signal (the signal from another path from the Splitter to the Mixer M2; it is common that either the mixer or the splitter would introduce a phase shift).
Rideout et al does not state that a clock signal is received and an output converter is used.
Regarding the clock signal, however, first, Rideout et al discloses that the system shown in Figure 1 can be used for radio-over-fiber (RoF) (page 2344, I. Introduction, and II. Design and Analysis), and the Down-conversion circuit (the combination of Photodetector, Amp 1 and Down-conversion module in Figure 1) down-converts the optical signal (Rideout: page 2344, II. Design And Analysis, “In this new configuration, to generate a microwave signal at 11.2 GHz, S1 is chosen to operate at 12 GHz, so that the frequency discriminator now operates at the offset frequency of these two, which is 800 MHz. The discriminator, a two-tap delay line filter, is designed by controlling the delay line length such that is has an operating null at 800 MHz. A DC feedback proportional to the difference between the down-converted frequency and the 800-MHz null is generated and sent to the master laser to maintain a fixed wavelength difference corresponding to 11.2 GHz”). Figure O1 in page 5 of this Office-Action shows a comparison between Applicant’s Figure 12 (claimed features) and Figure 1 of Rideout.
As shown in Figure O1, Applicant discloses two lasers (primary laser and secondary laser), and Rideout et al also discloses two lasers (Master laser and Slave laser); Applicant discloses a feedback control loop path, and Rideout et al also discloses a feedback control loop path; Applicant discloses a Down-conversion circuitry, and Rideout et al also discloses a Down-conversion circuitry; Applicant discloses a Phase Detector, and Rideout et al also discloses a Phase Detector. The only different is that Applicant uses a digital frequency discriminator (DFD), but Rideout et al uses a Frequency Discriminator (may not a digital frequency discriminator). Therefore, it is obvious to one skilled in the art that the system/method disclosed by Rideout can be used to control/stabilize a laser source that generates a clock signal.
Second, to use a laser to generate a clock signal or local oscillator signal is well known in the art. E.g., Middleton et al discloses a wireless communication system/method with optical carriers et al (Figures 2 and 4), in which a laser (28 in Figure 2; or a set of CW laser 62) generates a clock signal (modulated by the local oscillator 32 via the modulator 30), “a modulated optical carrier signal commensurate of the LO frequency” ([0028]). Also, another prior art, Ryu et al, discloses a system/method (Figure 3) in which a frequency discriminator (10) is used to control the frequency of the local oscillator laser (2) (column 3 lines 29-68).
The combination of Mehrgardt and Noguchi and Relph discloses a digital frequency discriminator with an input converter (ADC) and an output converter (DAC). A digital frequency discriminator has the advantage of greater accuracy, flexibility, and noise immunity, along with benefits like easier integration into complex system. Therefore, it would have been obvious to one skilled in the art that a digital frequency discriminator can be used in the system of Rideout so to controlling the clock signal or local oscillator more accurately. And the combination of Mehrgardt and Noguchi and Relph discloses an output converter (DAC); therefore, while a digital frequency discriminator is incorporated into the system shown in Figure 1 of Rideout, it is obvious that the output converter (DAC), which is disclosed by Mehrgardt and Noguchi and Relph, can convert the control signal from a digital domain to an analog domain so to control the master laser.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to combine Rideout et al and Middleton et al and Ryu et al with Mehrgardt and Noguchi and Relph so that a digital frequency discriminator is used to stabilize the frequency/phase of a local oscillator having a clock signal.
Claims 19-20 are rejected under 35 U.S.C. 103 as being unpatentable over Rideout et al (Rideout et al: “Discriminator-Aided Optical Phase-Lock Loop Incorporating a Frequency Down-Conversion Module”, IEEE Photonics Technology Letters, November 15, 2006, Vol. 8, No. 22, pages 2344-2346) in view of Kim et al (US 2022/0303017) and Mehrgardt (US 4,634,989).
1). With regard to claim 19, Rideout et al discloses an electronic device comprising:
a first light source (Figure 1, the Master Laser) configured to generate a first optical signal;
a second light source (Figure 1, the Slave Laser) configured to generate a second signal; and
a frequency discriminator (the Frequency Discriminator) coupled between an output of the first light source (the output of the Master laser, and then PD -> Down-conversion -> Splitter -> Frequency Discriminator) and an input of the first light source (the input of the Master Laser that accepts the signal from the Frequency Discriminator), the frequency discriminator including
a splitter (in the Frequency Discriminator) to accept an input signal (from the Down-Conversion/Splitter)
circuitry (e.g., the Splitter/Mixer M2, Delay Line and Low-pass filter LP2 etc.) configured to generate a control signal based on the input signal, the control signal being indicative of a phase noise of the input signal (page 2345, B. Phase Noise Analysis and III. Results etc.).
But, Rideout et al does not expressly disclose: an antenna radiating element; a photodiode coupled to the antenna radiating element; the first light source configured to generate a first optical local oscillator (LO) signal that illuminates the photodiode; the second light source configured to generate a second optical LO signal that illuminates the photodiode; and the frequency discriminator including a converter configured to convert an input signal into a digital signal, and digital circuitry configured to generate a control signal based on the digital signal.
Regarding the antenna etc., first, Rideout discloses that the system shown in Figure 1 can be used for radio-over-fiber (RoF) (page 2344, I. Introduction, and II. Design and Analysis). Figure O1 in page 5 of this Office-Action shows a comparison between Applicant’s Figure 12 (claimed features) and Figure 1 of Rideout.
As shown in Figure O1, Applicant discloses two lasers (primary laser and secondary laser), and Rideout et al also discloses two lasers (Master laser and Slave laser); Applicant discloses a feedback control loop path, and Rideout et al also discloses a feedback control loop path; Applicant discloses a Down-conversion circuitry, and Rideout et al also discloses a Down-conversion circuitry; Applicant discloses a Phase Detector, and Rideout et al also discloses a Phase Detector. The only different is that Applicant uses a digital frequency discriminator (DFD), but Rideout et al uses a Frequency Discriminator (may not a digital frequency discriminator). The structure of Applicant’s system and Rideout’s system are the same. Therefore, it is obvious to one skilled in the art that the system/method disclosed by Rideout can be used for a RoF wireless communications.
Second, Kim et al discloses a light-based wireless transmission system (Figure 1) comprising: an antenna radiating element (170 in Figure 1); a photodiode (UTC-PD 160) coupled to the antenna radiating element; a first light source (e.g., laser 110, Local Oscillator) configured to generate a first optical local oscillator (LO) signal that illuminates the photodiode; a second light source (e.g., laser 120) configured to generate a second optical LO signal that illuminates the photodiode; an antenna radiating element (179), and a photodiode (160) configured to produce an antenna current on the antenna radiating element based on the optical LO signal (from local oscillator 110).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to apply the teachings of Kim et al to the system/method of Rideout et al so that the system/method can be used in a RoF wireless communication system and to obtain a frequency and phase stabilized local oscillator.
Regarding the digital frequency oscillator, a digital frequency discriminator is well known in the art and commercially available. E.g., Mehrgardt discloses a digital frequency discriminator (Figure 1 etc.) including a converter (A/D converter “aw” in Figure 1) configured to convert an input signal (signal “a1”) into a digital signal, and digital circuitry (a digital delays “v1”/“v2”, a digital phase shifter “ht”, and mixer “ad” etc.) configured to generate an output signal based on the digital signal.
A digital frequency discriminator has the advantage of greater accuracy, flexibility, and noise immunity, along with benefits like easier integration into complex system. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to combine Mehrgardt with Rideout et al and Middleton et al so that a digital frequency discriminator is used for controlling the clock signal or local oscillator more accurately.
2). With regard to claim 20, Rideout et al and Kim et al and Mehrgardt disclose all of the subject matter as applied to claim 1 above. And the combination of Rideout et al and Kim et al and Mehrgardt further discloses the electronic device of claim 19, further comprising:
a phase detector (Rideout: Phase Detector, which includes a Reference source S2, Mixer M3 and Low Pass filter LP1) coupled between an output of the second light source (Slave Laser -> Photodetector -> Down-conversion -> Splitter -> Phase Detector) and an input of the second light source (the input of the Slave Laser); and
downconversion circuitry (Rideout: the combination of Photodetector, Amp 1 and Down-conversion module in Figure 1) coupled between the outputs of the first and second light sources, an input of the phase detector, and an input of the frequency discriminator (Maser Laser/Slave Laser -> Photodetector -> Down-conversion -> Splitter -> Phase Detector/Frequency Discriminator).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 20220393690 A1
US 11418199 B1
US 11075642 B2
US 20190319356 A1
US 20100237958 A1
US 20020167708 A1
US 20020012495 A1
US 5828238 A
US 5519389 A
US 5247308 A (a frequency discriminator, Figure 3, and the splitter 12 is also a phase shifter that shifts a phase of one path by 90o; column 2 lines 52-59, “The input signal from a compressive receiver 10 is split into two paths by a 90o phase shifter 12, one passing through a delay network 14 and the other applied directly to the reference port 16a of a phase comparator 16. The delay line introduces a constant delay of t seconds over the bandwidth of interest.”)
US 5115332 A
US 4918405 A
US 4890071 A
US 4888557 A
US 4728957 A
US 3624523 A
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/LI LIU/Primary Examiner, Art Unit 2634 September 19, 2025