Patents by Inventor Shutong Zhou
Shutong Zhou 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).
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Patent number: 7873285Abstract: This anti clipping circuit is for a laser transmitter used to transmit sub-carrier multiplexed signals for CATV applications. The circuit design is based on actual clipping measurements showing the specific time and duration of the clipping events is random. The individual clipping pulses interval is fixed, every 4 us. A PHEMT peak detection circuit is used in conjunction with a missing pulse detector/timer to catch all the clipping events. Thus the laser bias current is adjusted automatically at the specific time of the clipping event and for the duration of all the clipping pulses in the event. The controlled increase and decrease of the lasers bias current is DC coupled back into the normal DC bias path via a diode. This gives the anti clipping circuit noise isolation when there are no clipping events and avoids laser clipping during the laser current recovery time as when using an AC coupling scheme.Type: GrantFiled: May 23, 2007Date of Patent: January 18, 2011Assignee: General Instrument CorporationInventors: Shutong Zhou, Richard A. Meier
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Patent number: 7809282Abstract: Improved dispersion compensating circuits for optical transmission systems are disclosed. According to the improved method, there is provided a compensation circuit comprising a varactor diode network. The network is preferably inserted between a source of laser modulating signal and the laser. A low pass filter constructs the network. The network preferably includes an inductance and a combined circuit, which includes varactors. The network preferably provides an amplitude dependent delay of the modulating signal applied to the laser. In a first embodiment, a fixed capacitor is in series with a varactor and connected to a DC bias through inductor. In a second embodiment, second varactor is in series with varactor instead with an opposite polarity of a fixed capacitor as used in the first embodiment. In a third embodiment, two varactors 301 and 302 are used in place of the fixed capacitor in parallel.Type: GrantFiled: May 12, 2006Date of Patent: October 5, 2010Assignee: General Instrument CorporationInventor: Shutong Zhou
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Patent number: 7792165Abstract: Improved dispersion compensating circuits for optical transmission systems are disclosed. According to the improved method, there is provided a compensation circuit comprising a varactor diode network. The network is preferably inserted between a source of laser modulating signal and the laser. A low-pass filter or all pass filter constructs the network. The network preferably includes an inductor or inductors and a combined circuit, which includes varactors. The network preferably provides an amplitude dependent delay of the modulating signal applied to the laser or to the optical receiver as post dispersion correction circuitry. In a first embodiment, a fixed capacitor is in series with a varactor and connected to a DC bias through inductor. Additional embodiments, using multiple varactors in different circuit configurations, with particular advantages for various applications identified.Type: GrantFiled: March 31, 2008Date of Patent: September 7, 2010Assignee: General Instrument CorporationInventors: Ihab Khalouf, Richard Meier, Shutong Zhou
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Patent number: 7606502Abstract: A predistortion generator for coupling in-line with a non-linear device produces an output predistortion signal of useful amplitude, but with low composite triple beat and cross modulation distortions. The predistortion circuit comprises a distortion circuit which utilizes the non-linear current flowing through at least one diode, to provide a desired amount of signal attenuation bandwidth. The distortion generator circuitry is always matched to the non-linear device, thereby ensuring a frequency response that is predictable and predefined.Type: GrantFiled: December 19, 2006Date of Patent: October 20, 2009Assignee: General Instrument CorporationInventor: Shutong Zhou
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Publication number: 20090245309Abstract: Improved dispersion compensating circuits for optical transmission systems are disclosed. According to the improved method, there is provided a compensation circuit comprising a varactor diode network. The network is preferably inserted between a source of laser modulating signal and the laser. A low-pass filter or all pass filter constructs the network. The network preferably includes an inductor or inductors and a combined circuit, which includes varactors. The network preferably provides an amplitude dependent delay of the modulating signal applied to the laser or to the optical receiver as post dispersion correction circuitry. In a first embodiment, a fixed capacitor is in series with a varactor and connected to a DC bias through inductor. Additional embodiments, using multiple varactors in different circuit configurations, with particular advantages for various applications identified.Type: ApplicationFiled: March 31, 2008Publication date: October 1, 2009Applicant: GENERAL INSTRUMENT CORPORATIONInventors: Ihab Khalouf, Richard Meier, Shutong Zhou
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Publication number: 20080292315Abstract: This anti clipping circuit is for a laser transmitter used to transmit sub-carrier multiplexed signals for CATV applications. The circuit design is based on actual clipping measurements showing the specific time and duration of the clipping events is random. The individual clipping pulses interval is fixed, every 4 us. A PHEMT peak detection circuit is used in conjunction with a missing pulse detector/timer to catch all the clipping events. Thus the laser bias current is adjusted automatically at the specific time of the clipping event and for the duration of all the clipping pulses in the event. The controlled increase and decrease of the lasers bias current is DC coupled back into the normal DC bias path via a diode. This gives the anti clipping circuit noise isolation when there are no clipping events and avoids laser clipping during the laser current recovery time as when using an AC coupling scheme.Type: ApplicationFiled: May 23, 2007Publication date: November 27, 2008Applicant: GENERAL INSTRUMENT CORPORATIONInventors: Shutong Zhou, Richard A. Meier
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Publication number: 20070264027Abstract: Improved dispersion compensating circuits for optical transmission systems are disclosed. According to the improved method, there is provided a compensation circuit comprising a varactor diode network. The network is preferably inserted between a source of laser modulating signal and the laser. A low pass filter constructs the network. The network preferably includes an inductance and a combined circuit, which includes varactors. The network preferably provides an amplitude dependent delay of the modulating signal applied to the laser. In a first embodiment, a fixed capacitor is in series with a varactor and connected to a DC bias through inductor. In a second embodiment, second varactor is in series with varactor instead with an opposite polarity of a fixed capacitor as used in the first embodiment. In a third embodiment, two varactors 301 and 302 are used in place of the fixed capacitor in parallel.Type: ApplicationFiled: May 12, 2006Publication date: November 15, 2007Inventor: Shutong Zhou
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Publication number: 20070098414Abstract: A predistortion generator for coupling in-line with a non-linear device produces an output predistorion signal of useful amplitude, but with low composite triple beat and cross modulation distortions. The predistortion circuit comprises a distortion circuit which utilizes the non-linear current flowing through at least one diode, to provide a desired amount of signal attenuation bandwidth. The distortion generator circuitry is always matched to the non-linear device, thereby ensuring a frequency response that is predictable and predefined.Type: ApplicationFiled: December 19, 2006Publication date: May 3, 2007Inventor: Shutong Zhou
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Patent number: 6985020Abstract: An inline predistortion circuit for producing composite second order (CSO) and composite triple beat (CTB) distortion correction of a laser transmitter is disclosed having an RF input signal, a diode for producing nonlinear current, and a DC voltage bias for controlling the nonlinear current. The predistortion circuit lacks DC blocking capacitors between the RF attenuator and the diode, which results in improved nonlinear current generation across a wide frequency range. A capacitor in parallel with the bias circuit further increases diode's capability for producing nonlinear current. A low resistance resistor in series with the RF signal path and in parallel with the diode provides the voltage necessary for the diode to conduct while minimizing RF signal attenuation. An inductor in series with the RF signal provides improved phase correction of the CSO and CTB predistortion circuit.Type: GrantFiled: July 9, 2002Date of Patent: January 10, 2006Assignee: General Instrument CorporationInventor: Shutong Zhou
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Patent number: 6865199Abstract: A method is provided for using an uncooled laser package having pre-established performance specifications that include a pre-established optical power level. The package is to be used at a second set of performance specifications that include a second optical power level greater than the preestablished optical power level. The method begins by applying a bias level to a laser diode in the uncooled laser package that optimizes distortion and causes the laser package to generate the second optical power level. The bias level is greater than a pre-established bias level specified to generate the pre-established optical power level. Next, the uncooled laser package is heated or cooled to maintain a substantially constant laser diode temperature.Type: GrantFiled: July 29, 2002Date of Patent: March 8, 2005Assignee: General Instrument CorporationInventors: Philip Miguelez, Shutong Zhou, Richard A. Meier, N. John Nagurny
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Publication number: 20040052536Abstract: A predistortion generator for coupling in-line with a non-linear device produces an output predistorion signal of useful amplitude, but with low composite triple beat and cross modulation distortions. The predistortion circuit comprises a distortion circuit which utilizes the non-linear current flowing through at least one diode, to provide a desired amount of signal attenuation bandwidth. The distortion generator circuitry is always matched to the non-linear device, thereby ensuring a frequency response that is predictable and predefined.Type: ApplicationFiled: September 17, 2002Publication date: March 18, 2004Applicant: General Instrument CorporationInventor: Shutong Zhou
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Publication number: 20040008083Abstract: An inline predistortion circuit for producing composite second order (CSO) and composite triple beat (CTB) distortion correction of a laser transmitter is disclosed having an RF input signal, a diode for producing nonlinear current, and a DC voltage bias for controlling the nonlinear current. The predistortion circuit lacks DC blocking capacitors between the RF attenuator and the diode, which results in improved nonlinear current generation across a wide frequency range. A capacitor in parallel with the bias circuit further increases diode's capability for producing nonlinear current. A low resistance resistor in series with the RF signal path and in parallel with the diode provides the voltage necessary for the diode to conduct while minimizing RF signal attenuation. An inductor in series with the RF signal provides improved phase correction of the CSO and CTB predistortion circuit.Type: ApplicationFiled: July 9, 2002Publication date: January 15, 2004Applicant: General Instrument CorporationInventor: Shutong Zhou
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Patent number: 6577177Abstract: An in-line distortion generator for coupling in-line with a non-linear device (NLD) produces an output signal of useful amplitude, but with low composite triple beat and cross modulation distortions. The distortion generator comprises an instant controlled non-linear attenuator which utilizes the non-linear current flowing through a pair of diodes to provide the proper amount of signal attenuation over the entire frequency bandwidth. The distortion generator circuitry is always matched to the NLD, thereby ensuring a frequency response that is predictable and predefined. The distortion generator may also include a temperature compensation circuit to ensure consistent operation throughout a wide temperature range.Type: GrantFiled: April 1, 1999Date of Patent: June 10, 2003Assignee: General Instrument CorporationInventors: Shutong Zhou, Timothy J. Brophy, Richard A. Meier
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Patent number: 6570430Abstract: An in-line distortion generator for coupling in-line with a non-linear device (NLD) produces an output signal of useful amplitude, but with low composite second order, composite triple beat and cross modulation distortions. The distortion generator comprises an instant controlled non-linear attenuator which utilizes the non-linear current flowing through a pair of diodes, in parallel with a resistor and an inductor, to provide the proper amount of signal attenuation over the entire frequency bandwidth. The distortion generator circuitry is always matched to the NLD, thereby ensuring a frequency response that is predictable and predefined. The distortion generator may also include a temperature compensation circuit to ensure consistent operation throughout a wide temperature range.Type: GrantFiled: January 29, 2002Date of Patent: May 27, 2003Assignee: General Instrument CorporationInventor: Shutong Zhou
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Publication number: 20030072337Abstract: A method is provided for using an uncooled laser package having pre-established performance specifications that include a pre-established optical power level. The package is to be used at a second set of performance specifications that include a second optical power level greater than the preestablished optical power level. The method begins by applying a bias level to a laser diode in the uncooled laser package that optimizes distortion and causes the laser package to generate the second optical power level. The bias level is greater than a pre-established bias level specified to generate the pre-established optical power level. Next, the uncooled laser package is heated or cooled to maintain a substantially constant laser diode temperature.Type: ApplicationFiled: July 29, 2002Publication date: April 17, 2003Inventors: Philip Miguelez, Shutong Zhou, Richard A. Meier, N. John Nagurny
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Publication number: 20030063637Abstract: A method is provided for maintaining the temperature of a laser diode located in a laser package. The method begins by monitoring a photocurrent generated by a photodiode that collects light from a back-facet of the laser diode located in the laser package while maintaining a constant bias level to the laser diode. Next, the laser diode is heated or cooled to maintain a substantially constant photocurrent, thereby maintaining the temperature of the laser diode at a substantially constant value. The laser package may be an uncooled laser package such as a coaxial can laser package.Type: ApplicationFiled: July 29, 2002Publication date: April 3, 2003Inventors: Philip Miguelez, Shutong Zhou, Richard A. Meier, N. John Nagurny
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Publication number: 20010054927Abstract: An in-line distortion generator for coupling in-line with a non-linear device (NLD) produces an output signal of useful amplitude, but with low composite triple beat and cross modulation distortions. The distortion generator comprises an instant controlled non-linear attenuator which utilizes the non-linear current flowing through a pair of diodes to provide the proper amount of signal attenuation over the entire frequency bandwidth. The distortion generator circuitry is always matched to the NLD, thereby ensuring a frequency response that is predictable and predefined. The distortion generator may also include a temperature compensation circuit to ensure consistent operation throughout a wide temperature range.Type: ApplicationFiled: April 1, 1999Publication date: December 27, 2001Inventors: SHUTONG ZHOU, TIMOTHY J. BROPHY, RICHARD MEIER
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Patent number: 6232836Abstract: A plurality of amplifiers are connected in cascade to form an in-line predistortion circuit. The amplifiers are unbalanced in that each amplifier stage in the circuit has two DC voltage rails which are independently controlled to provide different, i.e. offset, DC voltage levels to the unbalanced amplifiers. This unbalance in the amplifiers generates predistortion in a signal which can be used to cancel the inherent distortion caused by a non-linear device which subsequently processes or transmits the predistorted signal. Control of the DC voltage offset in at least one of the amplifier stages is necessary to match the predistortion to the inherent distortion being corrected. A tilt circuit can be used in cascade with the plurality of amplifiers (in front of the RF amplifiers) to compensate the amplitude change caused by the unbalanced RF amplifiers. Either side of the DC voltage can be changed in order to correct for either sublinear or superlinear laser diode curves.Type: GrantFiled: May 11, 2000Date of Patent: May 15, 2001Assignees: General Instrument Corporation, Motorola Inc.Inventor: Shutong Zhou
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Patent number: 6133790Abstract: A plurality of amplifiers are connected in cascade to form an in-line predistortion circuit. The amplifiers are unbalanced in that each amplifier stage in the circuit has two DC voltage rails which are independently controlled to provide different, i.e. offset, DC voltage levels to the unbalanced amplifiers. This unbalance in the amplifiers generates predistortion in a signal which can be used to cancel the inherent distortion caused by a non-linear device which subsequently processes or transmits the predistorted signal. Control of the DC voltage offset in at least one of the amplifier stages is necessary to match the predistortion to the inherent distortion being corrected. A tilt circuit can be used in cascade with the plurality of amplifiers (in front of the RF amplifiers) to compensate the amplitude change caused by the unbalanced RF amplifiers. Either side of the DC voltage can be changed in order to correct for either sublinear or superlinear laser diode curves.Type: GrantFiled: September 17, 1998Date of Patent: October 17, 2000Assignee: Motorola, Inc.Inventor: Shutong Zhou
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Patent number: 6107877Abstract: An in-line distortion generator is coupled to an RF amplifier on a single PC board for producing an output signal of useful amplitude but with low composite triple beat and cross modulation distortions. The backplane under the section of the PC board upon which the distortion circuit resides is removed and the portion of the heat sink under the removed portion of the backplane is also removed. This eliminates any parasitic capacitances that could degrade the performance of the RF amplifier, thereby making the distortion circuit transparent to the RF amplifier. Furthermore, the layout of the predistortion circuitry has been specifically designed to enhance the performance of the circuitry without inducing any negative operating characteristics on the associated RF amplifier.Type: GrantFiled: April 9, 1999Date of Patent: August 22, 2000Assignee: General Instrument CorporationInventors: Philip Miguelez, Rudolph Menna, Shutong Zhou, Timothy Cope