Patents by Inventor Radhakrishnan L. Nagarajan

Radhakrishnan L. Nagarajan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20190036610
    Abstract: The present invention relates to telecommunication techniques and integrated circuit (IC) devices. More specifically, embodiments of the present invention provide an off-quadrature modulation system. Once an off-quadrature modulation position is determined, a ratio between DC power transfer amplitude and dither tone amplitude for a modulator is as a control loop target to stabilize off-quadrature modulation. DC power transfer amplitude is obtained by measuring and sampling the output of an optical modulator. Dither tone amplitude is obtained by measuring and sampling the modulator output and performing calculation using the optical modulator output values and corresponding dither tone values. There are other embodiments as well.
    Type: Application
    Filed: September 28, 2018
    Publication date: January 31, 2019
    Inventors: Todd ROPE, Radhakrishnan L. NAGARAJAN, Hari SHANKAR
  • Patent number: 10187143
    Abstract: In an example, the present invention includes an integrated system-on-chip device. The device is configured on a single silicon substrate member. The device has a data input/output interface provided on the substrate member. The device has an input/output block provided on the substrate member and coupled to the data input/output interface. The device has a signal processing block provided on the substrate member and coupled to the input/output block. The device has a driver module provided on the substrate member and coupled to the signal processing block. In an example, the device has a driver interface provided on the substrate member and coupled to the driver module and configured to be coupled to a silicon photonics device. In an example, a control block is configured to receive and send instruction(s) in a digital format to the communication block and is configured to receive and send signals in an analog format to communicate with the silicon photonics device.
    Type: Grant
    Filed: May 9, 2018
    Date of Patent: January 22, 2019
    Assignee: INPHI CORPORATION
    Inventor: Radhakrishnan L. Nagarajan
  • Patent number: 10187710
    Abstract: In an example, the present invention includes an integrated system on chip device. The device has a data input/output interface provided on the substrate member and configured for a predefined data rate and protocol. In an example, the data input/output interface is configured for number of lanes numbered from four to one hundred and fifty. In an example, the SerDes block is configured to convert a first data stream of N into a second data stream of M such that each of the first data stream having a first predefined data rate at a first clock rate and each of the second data stream having a second predefined data rate at a second clock rate.
    Type: Grant
    Filed: August 7, 2017
    Date of Patent: January 22, 2019
    Assignee: INPHI CORPORATION
    Inventor: Radhakrishnan L. Nagarajan
  • Publication number: 20190013872
    Abstract: The present invention is directed to communication systems and methods. In a specific embodiment, the present invention provides an optical receiver that receives a data stream from an optical transmitter. The optical receiver determines a histogram contour parameter using the data stream and inserts the histogram contour parameter into a back-channel data segment, which is then transmitted to the optical transmitter. The optical transmitter changes its data transmission setting based on the histogram contour parameter. There are other embodiments as well.
    Type: Application
    Filed: July 7, 2017
    Publication date: January 10, 2019
    Inventors: Todd ROPE, Hari SHANKAR, Radhakrishnan L. NAGARAJAN
  • Publication number: 20180375587
    Abstract: The present invention is directed to a communication signal tracking system comprising an optical receiver including one or more delay line interferometers (DLIs) configured to demultiplex incoming optical signals and a transimpedance amplifier configured to convert the incoming optical signals to incoming electrical signals. The communication signal tracking system further includes a control module configured to calculate a bit-error-rate (BER) of the incoming electrical signals before forward-error correction decoding, and use the BER as a parameter for optimizing settings of the one or more DLIs in one or more iterations in a control loop and generating a back-channel data.
    Type: Application
    Filed: June 26, 2017
    Publication date: December 27, 2018
    Inventors: Todd ROPE, Sung CHOI, James STEWART, Radhakrishnan L. NAGARAJAN, Paul YU, Ilya LYUBOMIRSKY
  • Patent number: 10164405
    Abstract: A wavelength locker integrated with a silicon photonics transmission system comprising a silicon-on-insulator (SOI) substrate and an input via a power tap coupler to receive a fraction of a transmission signal with one or more frequencies from a primary output path of the silicon photonics transmission system. The wavelength locker further includes a splitter configured to split the input to a first signal in a first path and a second signal in a second path and a first delay-line-interferometer (DLI) coupled to the second path to receive the second signal and configured to generate an interference spectrum and output at least two sub-spectrums tunable to keep quadrature points of the sub-spectrums at respective one or more target frequencies. The wavelength locker is configured to generate an error signal fed back to the silicon photonics transmission system for locking the one or more frequencies at the one or more target frequencies.
    Type: Grant
    Filed: July 19, 2018
    Date of Patent: December 25, 2018
    Assignee: INPHI CORPORATION
    Inventors: Brian Taylor, Radhakrishnan L. Nagarajan, Masaki Kato
  • Patent number: 10141717
    Abstract: A packaged transmitter device includes a base member comprising a planar part mounted with a thermoelectric cooler, a transmitter, and a coupling lens assembly, and an assembling part connected to one side of the planar part. The device further includes a circuit board bended to have a first end region and a second end region being raised to a higher level. The first end region disposed on a top surface of the planar part includes multiple electrical connection patches respectively connected to the thermoelectric and the transmitter. The second end region includes an electrical port for external connection. Additionally, the device includes a cover member disposed over the planar part. Furthermore, the device includes a cylindrical member installed to the assembling part for enclosing an isolator aligned to the coupling lens assembly along its axis and connected to a fiber to couple optical signal from the transmitter to the fiber.
    Type: Grant
    Filed: December 27, 2017
    Date of Patent: November 27, 2018
    Assignees: INPHI CORPORATION, LUXNET CORPORATION
    Inventors: Radhakrishnan L. Nagarajan, Peng-Chih Li, Pi-Cheng Law
  • Patent number: 10142032
    Abstract: A silicon photonics based temperature-insensitive delay line interferometer (DLI). The DLI includes a first arm comprising a first length of a first material characterized by a first group index corresponding to a first phase delay to transfer a first light wave with a first peak frequency and a second arm comprising a second length of a second material characterized by a second group index corresponding to a second phase to transfer a second light wave with a second peak frequency with a time-delay difference relative to the first light wave. The first phase delay and the second phase delay are configured to change equally upon a change of temperature. The time-delay difference between the first light wave and the second light wave is set to be inversed value of a free spectral range (FSR) to align at least the first peak frequency to a channel of a designated frequency grid.
    Type: Grant
    Filed: February 7, 2018
    Date of Patent: November 27, 2018
    Assignee: INPHI CORPORATION
    Inventors: Masaki Kato, Radhakrishnan L. Nagarajan
  • Publication number: 20180337745
    Abstract: An integrated apparatus with optical/electrical interfaces and protocol converter on a single silicon substrate. The apparatus includes an optical module comprising one or more modulators respectively coupled with one or more laser devices for producing a first optical signal to an optical interface and one or more photodetectors for detecting a second optical signal from the optical interface to generate a current signal. Additionally, the apparatus includes a transmit lane module coupled between the optical module and an electrical interface to receive a first electric signal from the electrical interface and provide a framing protocol for driving the one or more modulators. Furthermore, the apparatus includes a receive lane module coupled between the optical module and the electrical interface to process the current signal to send a second electric signal to the electrical interface.
    Type: Application
    Filed: July 13, 2018
    Publication date: November 22, 2018
    Inventor: Radhakrishnan L. NAGARAJAN
  • Patent number: 10133004
    Abstract: An apparatus for converting fiber mode to waveguide mode. The apparatus includes a silicon substrate member and a dielectric member having an elongated body. Part of the elongated body from a back end overlies the silicon substrate member and remaining part of the elongated body up to a front end is separated from the silicon substrate member by a second dielectric material at an under region. The apparatus also includes a waveguide including a segment from the back end to a tail end formed on the dielectric member at least partially overlying the remaining part of the elongated body. The segment is buried in a cladding overlying entirely the dielectric member. The cladding has a refractive index that is less than the waveguide but includes an index-graded section with decreasing index that is formed at least over the segment from the tail end toward the back end.
    Type: Grant
    Filed: March 22, 2018
    Date of Patent: November 20, 2018
    Assignee: INPHI CORPORATION
    Inventors: Masaki Kato, Radhakrishnan L. Nagarajan
  • Publication number: 20180329852
    Abstract: The present invention provides an integrated system-on-chip device. The device is configured on a single silicon substrate member. The device has a data input/output interface provided on the substrate member. The device has an input/output block provided on the substrate member and coupled to the data input/output interface. The device has a signal processing block provided on the substrate member and coupled to the input/output block. The device has a driver module provided on the substrate member and coupled to the signal processing block. The device further includes a driver interface and coupled to the driver module and configured to be coupled to a silicon photonics device. In an example, a control block is configured to receive and send instruction(s) in a digital format to the communication block and is configured to receive and send signals in an analog format to communicate with the silicon photonics device.
    Type: Application
    Filed: July 20, 2018
    Publication date: November 15, 2018
    Inventors: Siddharth SHETH, Radhakrishnan L. NAGARAJAN
  • Patent number: 10128955
    Abstract: A Pulse Amplitude Modulated (PAM) optical device utilizing multiple wavelengths, features a communications interface having enhanced diagnostics capability. New registers are created to house additional diagnostic information, such as error rates. The diagnostic information may be stored in raw form, or as processed on-chip utilizing local resources.
    Type: Grant
    Filed: May 25, 2018
    Date of Patent: November 13, 2018
    Assignee: INPHI CORPORATION
    Inventors: Todd Rope, Radhakrishnan L. Nagarajan, Jamal Riani, Pulkit Khandelwal
  • Patent number: 10126629
    Abstract: An optical dispersion compensator integrated with a silicon photonics system including a first phase-shifter coupled to a second phase-shifter in parallel on the silicon substrate characterized in an athermal condition. The dispersion compensator further includes a third phase-shifter on the silicon substrate to the first phase-shifter and the second phase-shifter through two 2×2 splitters to form an optical loop. A second entry port of a first 2×2 splitter is for coupling with an input fiber and a second exit port of a second 2×2 splitter is for coupling with an output fiber. The optical loop is characterized by a total phase delay tunable via each of the first phase-shifter, the second phase-shifter, and the third phase-shifter such that a normal dispersion (>0) at a certain wavelength in the input fiber is substantially compensated and independent of temperature.
    Type: Grant
    Filed: August 3, 2017
    Date of Patent: November 13, 2018
    Assignee: INPHI CORPORATION
    Inventors: Xiaoguang Tu, Radhakrishnan L. Nagarajan, Masaki Kato
  • Publication number: 20180321519
    Abstract: An integrated differential Electro-Absorption Modulator (EAM) device. The device includes a substrate, an electrical driver, and two EAM modules. The electrical driver circuit is configured overlying the substrate member and has one output electrically coupled to the first EAM module and the other output electrically coupled to the second EAM module. The first and second EAM modules have a first and a second output, respectively. A beam splitter can be configured to split an optical input into two optical outputs, each of which can be optically coupled to the optical inputs of the first and second EAM modules.
    Type: Application
    Filed: July 2, 2018
    Publication date: November 8, 2018
    Inventor: Radhakrishnan L. NAGARAJAN
  • Publication number: 20180323577
    Abstract: A wavelength locker integrated with a silicon photonics transmission system comprising a silicon-on-insulator (SOI) substrate and an input via a power tap coupler to receive a fraction of a transmission signal with one or more frequencies from a primary output path of the silicon photonics transmission system. The wavelength locker further includes a splitter configured to split the input to a first signal in a first path and a second signal in a second path and a first delay-line-interferometer (DLI) coupled to the second path to receive the second signal and configured to generate an interference spectrum and output at least two sub-spectrums tunable to keep quadrature points of the sub-spectrums at respective one or more target frequencies. The wavelength locker is configured to generate an error signal fed back to the silicon photonics transmission system for locking the one or more frequencies at the one or more target frequencies.
    Type: Application
    Filed: July 19, 2018
    Publication date: November 8, 2018
    Inventors: Brian TAYLOR, Radhakrishnan L. NAGARAJAN, Masaki KATO
  • Patent number: 10120826
    Abstract: The present invention provides an integrated system-on-chip device. The device is configured on a single silicon substrate member. The device has a data input/output interface provided on the substrate member. The device has an input/output block provided on the substrate member and coupled to the data input/output interface. The device has a signal processing block provided on the substrate member and coupled to the input/output block. The device has a driver module provided on the substrate member and coupled to the signal processing block. The device further includes a driver interface and coupled to the driver module and configured to be coupled to a silicon photonics device. In an example, a control block is configured to receive and send instruction(s) in a digital format to the communication block and is configured to receive and send signals in an analog format to communicate with the silicon photonics device.
    Type: Grant
    Filed: November 13, 2017
    Date of Patent: November 6, 2018
    Assignee: INPHI CORPORATION
    Inventors: Siddharth Sheth, Radhakrishnan L. Nagarajan
  • Patent number: 10120150
    Abstract: An optical transceiver by hybrid multichip integration. The optical transceiver includes a PCB with a plurality of prefabricated surface bonding sites. A first chip includes a FOWLP package of multiple electronics devices embedded in a dielectric molding layer overlying a dielectric redistribution layer is disposed on the PCB by respectively bonding a plurality of conductor balls between the dielectric redistribution layer and the plurality of prefabricated surface bonding sites while exposing soldering material filled in multiple through-mold vias (TMVs) in the dielectric molding layer. The optical transceiver further includes a second chip configured as a Sipho die comprising photonics devices embedded in a SOI wafer substantially free from any electronics device process. The second chip is stacked over the first chip with multiple conductor bumps being bonded respectively to the soldering material in the multiple TMVs.
    Type: Grant
    Filed: May 21, 2018
    Date of Patent: November 6, 2018
    Assignee: INPHI CORPORATION
    Inventors: Liang Ding, Radhakrishnan L. Nagarajan, Roberto Coccioli
  • Patent number: 10120825
    Abstract: The present invention provides an integrated system-on-chip device. The device is configured on a single silicon substrate member. The device has a data input/output interface provided on the substrate member. The device has an input/output block provided on the substrate member and coupled to the data input/output interface. The device has a signal processing block provided on the substrate member and coupled to the input/output block. The device has a driver module provided on the substrate member and coupled to the signal processing block. The device further includes a driver interface and coupled to the driver module and configured to be coupled to a silicon photonics device. In an example, a control block is configured to receive and send instruction(s) in a digital format to the communication block and is configured to receive and send signals in an analog format to communicate with the silicon photonics device.
    Type: Grant
    Filed: October 11, 2017
    Date of Patent: November 6, 2018
    Assignee: INPHI CORPORATION
    Inventors: Siddharth Sheth, Radhakrishnan L. Nagarajan
  • Patent number: 10116393
    Abstract: A single chip dual-channel driver for two independent traveling wave modulators. The driver includes two differential pairs inputs per channel respectively configured to receive two digital differential pair signals. The driver further includes a two-bit DAC per channel coupled to the two differential pairs inputs to produce a single analog differential pair PAM signal at a differential pair output for driving a traveling wave modulator. Additionally, the driver includes a control block having internal voltage/current signal generators respective coupled to each input and the 2-bit DAC for providing a bias voltage, a tail current, a dither signal to assist modulation control per channel. Furthermore, the driver includes an internal I2C communication block coupled to a high-speed clock generator to generate control signals to the control block and coupled to host via an I2C digital communication interface.
    Type: Grant
    Filed: May 10, 2018
    Date of Patent: October 30, 2018
    Assignee: INPHI CORPORATION
    Inventors: Radhakrishnan L. Nagarajan, Todd Rope
  • Patent number: 10116391
    Abstract: The present invention relates to telecommunication techniques and integrated circuit (IC) devices. More specifically, embodiments of the present invention provide an off-quadrature modulation system. Once an off-quadrature modulation position is determined, a ratio between DC power transfer amplitude and dither tone amplitude for a modulator is as a control loop target to stabilize off-quadrature modulation. DC power transfer amplitude is obtained by measuring and sampling the output of an optical modulator. Dither tone amplitude is obtained by measuring and sampling the modulator output and performing calculation using the optical modulator output values and corresponding dither tone values. There are other embodiments as well.
    Type: Grant
    Filed: November 2, 2017
    Date of Patent: October 30, 2018
    Assignee: INPHI CORPORATION
    Inventors: Todd Rope, Radhakrishnan L. Nagarajan, Hari Shankar