Patents by Inventor Kan Tan

Kan Tan 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: 20200252246
    Abstract: An apparatus configured to acquire S-parameters of a communications channel includes a physical interface configured to transmit and receive signals through a communications channel under test, a processor, configured to execute instructions that, when executed cause the processor to: send a first data pattern from the transmitter through the communications channel at a first data rate; acquire a first waveform corresponding to the first data pattern and determine a first pulse response; calculate a first transfer function from the first pulse response; send a second data pattern from the transmitter through the communications channel at a second data rate; acquire a second waveform corresponding to the second data pattern and determine a second pulse response; calculate a second transfer function from the second pulse response; and combine the first and second transfer functions to determine an S-parameter of the communications channel.
    Type: Application
    Filed: January 29, 2020
    Publication date: August 6, 2020
    Applicant: Tektronix, Inc.
    Inventor: Kan Tan
  • Patent number: 10476704
    Abstract: Disclosed is a mechanism for limiting Intersymbol Interference (ISI) when measuring uncorrelated jitter in a test and measurement system. A waveform is obtained that describes a signal. Such waveform may be obtained from memory. A processor then extracts a signal impulse response from the waveform. The processor selects a window function based on a shape of the signal impulse response. Further, the processor applies the window function to the signal impulse response to remove ISI outside a window of the window function while measuring waveform jitter. The window function may be applied by applying the window function to the signal impulse response to obtain a target impulse response. A linear equalizer is then generated that results in the target impulse response when convolved with the signal impulse response. The linear equalizer is then applied to the waveform to limit ISI for jitter measurement.
    Type: Grant
    Filed: September 8, 2018
    Date of Patent: November 12, 2019
    Assignee: Tektronix, Inc.
    Inventor: Kan Tan
  • Patent number: 10432434
    Abstract: Systems and methods directed towards reducing noise introduced into a signal when processing the signal are discussed herein. In embodiments a signal may initially be split by a multiplexer into two or more frequency bands. Each of the frequency bands can then be forwarded through an assigned channel. One or more channels may include an amplifier to independently boost the signal band assigned to that channel prior to a noise source within the assigned channel. This results in boosting the signal band relative to noise introduced by the noise source. In some embodiments, a filter may also be implemented in one or more of the channels to remove noise from the channel that is outside the bandwidth of the signal band assigned to that channel. Additional embodiments may be described and/or claimed herein.
    Type: Grant
    Filed: June 8, 2017
    Date of Patent: October 1, 2019
    Assignee: Tektronix, Inc.
    Inventors: John J. Pickerd, Kan Tan, Pirooz Hojabri
  • Patent number: 10345339
    Abstract: Embodiments of the present invention provide techniques and methods for improving signal-to-noise ratio (SNR) when averaging two or more data signals by finding a group delay between the signals and using it to calculate an averaged result. In one embodiment, a direct average of the signals is computed and phases are found for the direct average and each of the data signals. Phase differences are found between each signal and the direct average. The phase differences are then used to compensate the signals. Averaging the compensated signals provides a more accurate result than conventional averaging techniques. The disclosed techniques can be used for improving instrument accuracy while minimizing effects such as higher-frequency attenuation. For example, in one embodiment, the disclosed techniques may enable a real-time oscilloscope to take more accurate S parameter measurements.
    Type: Grant
    Filed: April 29, 2016
    Date of Patent: July 9, 2019
    Assignee: Tektronix, Inc.
    Inventors: Kan Tan, John J. Pickerd
  • Patent number: 10274520
    Abstract: A test and measurement instrument, including a splitter configured to split an input signal into two split input signals and output each split input signal onto a separate path and a combiner configured to receive and combine an output of each path to reconstruct the input signal. Each path includes an amplifier configured to receive the split input signal and to compress the split input signal with a sigmoid function, a digitizer configured to digitize an output of the amplifier; and at least one processor configured to apply an inverse sigmoid function on the output of the digitizer.
    Type: Grant
    Filed: September 30, 2015
    Date of Patent: April 30, 2019
    Assignee: Tektronix, Inc.
    Inventors: John J. Pickerd, Kan Tan
  • Publication number: 20190103999
    Abstract: A continuously or step variable passive noise filter for removing noise from a signal received from a DUT added by a test and measurement instrument channel. The noise filter may include, for example, a splitter splits a signal into at least a first split signal and a second split signal. A first path receives the first split signal and includes a variable attenuator and/or a variable delay line which may be set based on the channel response of the DUT which is connected. The variable attenuator and/or the variable delay line may be continuously or stepped variable, as will be discussed in more detail below. A second path is also included to receive the second split signal and a combiner combines a signal from the first path and a signal from the second path into a combined signal.
    Type: Application
    Filed: August 29, 2018
    Publication date: April 4, 2019
    Applicant: Tektronix, Inc.
    Inventors: John J. Pickerd, Kan Tan, Pirooz Hojabri
  • Publication number: 20190068411
    Abstract: Disclosed is a mechanism for limiting Intersymbol Interference (ISI) when measuring uncorrelated jitter in a test and measurement system. A waveform is obtained that describes a signal. Such waveform may be obtained from memory. A processor then extracts a signal impulse response from the waveform. The processor selects a window function based on a shape of the signal impulse response. Further, the processor applies the window function to the signal impulse response to remove ISI outside a window of the window function while measuring waveform jitter. The window function may be applied by applying the window function to the signal impulse response to obtain a target impulse response. A linear equalizer is then generated that results in the target impulse response when convolved with the signal impulse response. The linear equalizer is then applied to the waveform to limit ISI for jitter measurement.
    Type: Application
    Filed: September 8, 2018
    Publication date: February 28, 2019
    Applicant: Tektronix, Inc.
    Inventor: Kan Tan
  • Patent number: 10209276
    Abstract: A method of employing a Decision Feedback Equalizer (DFE) in a test and measurement system. The method includes obtaining an input signal data associated with an input signal suffering from inter-symbol interference (ISI). A bit sequence encoded in the input signal data is determined to support assigning portions of the input signal data into sets based on the corresponding bit sequences. The DFE is applied to each set by employing a DFE slicer pattern corresponding to each set, which results in obtaining a DFE adjusted waveform histogram/PDF/waveform database graph for each set adjusted for ISI and accurately captures jitter suppression. The DFE adjusted waveform histogram/PDF/waveform database graphs are normalized and combined into a final histogram/PDF/waveform database graph for determining an eye contour of an eye diagram and jitter measurements.
    Type: Grant
    Filed: September 30, 2016
    Date of Patent: February 19, 2019
    Assignee: Tektronix, Inc.
    Inventor: Kan Tan
  • Patent number: 10145874
    Abstract: A method for determining scattering parameters of a device under test using a real-time oscilloscope. The method includes calculating a reflection coefficient of each port of a device under test with N ports, wherein N is greater than one, based on a first voltage measured by the real-time oscilloscope when a signal is generated from a signal generator. The method also includes determining an insertion loss coefficient of each port of the device under test, including calculating the insertion loss coefficient of the port of the device under test to be measured based on a second voltage measured by the real-time oscilloscope when a signal is generated from a signal generator.
    Type: Grant
    Filed: March 30, 2015
    Date of Patent: December 4, 2018
    Assignee: Tektronix, Inc.
    Inventors: Kan Tan, John J. Pickerd
  • Publication number: 20180262325
    Abstract: Disclosed is a mechanism for limiting Intersymbol Interference (ISI) when measuring uncorrelated jitter in a test and measurement system. A waveform is obtained that describes a signal. Such waveform may be obtained from memory. A processor then extracts a signal pulse from the waveform. The processor selects a window function based on a shape of the signal pulse. Further, the processor applies the window function to the signal pulse to remove ISI outside a window of the window function while measuring waveform jitter. The window function may be applied by applying the window function to the signal pulse to obtain a target pulse. A linear equalizer is then generated that results in the target pulse when convolved with the signal pulse. The linear equalizer is then applied to the waveform to limit ISI for jitter measurement.
    Type: Application
    Filed: August 25, 2017
    Publication date: September 13, 2018
    Applicant: Tektronix, Inc.
    Inventor: Kan Tan
  • Patent number: 10073750
    Abstract: A serial data link measurement and simulation system for use on a test and measurement instrument presents on a display device. A main menu having elements representing a measurement circuit, a simulation circuit and a transmitter. The main menu includes processing flow lines pointing from the measurement circuit to the transmitter and from the transmitter to the simulation circuit. The main menu includes a source input to the measurement circuit and one or more test points from which waveforms may be obtained. The simulation circuit includes a receiver. The measurement and simulation circuits are defined by a user, and the transmitter is common to both circuits so all aspects of the serial data link system are tied together.
    Type: Grant
    Filed: February 4, 2013
    Date of Patent: September 11, 2018
    Assignee: Tektronix, Inc.
    Inventors: John J. Pickerd, Kan Tan, Kalev Sepp, Sarah R. Boen
  • Patent number: 10075286
    Abstract: Disclosed is a mechanism for limiting Intersymbol Interference (ISI) when measuring uncorrelated jitter in a test and measurement system. A waveform is obtained that describes a signal. Such waveform may be obtained from memory. A processor then extracts a signal pulse from the waveform. The processor selects a window function based on a shape of the signal pulse. Further, the processor applies the window function to the signal pulse to remove ISI outside a window of the window function while measuring waveform jitter. The window function may be applied by applying the window function to the signal pulse to obtain a target pulse. A linear equalizer is then generated that results in the target pulse when convolved with the signal pulse. The linear equalizer is then applied to the waveform to limit ISI for jitter measurement.
    Type: Grant
    Filed: August 25, 2017
    Date of Patent: September 11, 2018
    Assignee: Tektronix, Inc.
    Inventor: Kan Tan
  • Patent number: 9933458
    Abstract: A test and measurement instrument including a splitter configured to split an input signal into at least two split signals, at least two harmonic mixers configured to mix an associated split signal with an associated harmonic signal to generate an associated mixed signal, at least two digitizers configured to digitize the associated mixed signal, at least two MIMO polyphase filter arrays configured to filter the associated digitized mixed signal of an associated digitizer of the at least two digitizers, at least two pairs of band separation filters configured to receive the associated digitized mixed signals from each of the MIMO polyphase filter arrays and output a low band of the input signal and a high band of the input signal based on a time different between the at least two digitizers and a phase drift of a local oscillator, and a combiner configured to combine the low band of the input signal and the high band of the input signal to form a reconstructed input signal.
    Type: Grant
    Filed: March 31, 2015
    Date of Patent: April 3, 2018
    Assignee: Tektronix, Inc.
    Inventors: John J. Pickerd, Kan Tan
  • Publication number: 20180045761
    Abstract: A method of employing a Decision Feedback Equalizer (DFE) in a test and measurement system. The method includes obtaining an input signal data associated with an input signal suffering from inter-symbol interference (ISI). A bit sequence encoded in the input signal data is determined to support assigning portions of the input signal data into sets based on the corresponding bit sequences. The DFE is applied to each set by employing a DFE slicer pattern corresponding to each set, which results in obtaining a DFE adjusted waveform histogram/PDF/waveform database graph for each set adjusted for ISI and accurately captures jitter suppression. The DFE adjusted waveform histogram/PDF/waveform database graphs are normalized and combined into a final histogram/PDF/waveform database graph for determining an eye contour of an eye diagram and jitter measurements.
    Type: Application
    Filed: September 30, 2016
    Publication date: February 15, 2018
    Inventor: Kan Tan
  • Publication number: 20180026816
    Abstract: Systems and methods directed towards reducing noise introduced into a signal when processing the signal are discussed herein. In embodiments a signal may initially be split by a multiplexer into two or more frequency bands. Each of the frequency bands can then be forwarded through an assigned channel. One or more channels may include an amplifier to independently boost the signal band assigned to that channel prior to a noise source within the assigned channel. This results in boosting the signal band relative to noise introduced by the noise source. In some embodiments, a filter may also be implemented in one or more of the channels to remove noise from the channel that is outside the bandwidth of the signal band assigned to that channel. Additional embodiments may be described and/or claimed herein.
    Type: Application
    Filed: June 8, 2017
    Publication date: January 25, 2018
    Inventors: John J. Pickerd, Kan Tan, Pirooz Hojabri
  • Publication number: 20170292977
    Abstract: Disclosed is a mechanism for reducing noise caused by an analog to digital conversion in a test and measurement system. An adaptive linear filter is generated based on a converted digital signal and measured signal noise. The adaptive linear filter includes a randomness suppression factor for alleviating statistical errors caused by a comparison of a signal circularity coefficient and a noise circularity coefficient in the adaptive linear filter. The adaptive linear filter is applied to the digital signal along with a stomp filter and a suppression clamp filter. The digital signal may be displayed in a complex frequency domain along with depictions of the adaptive linear filter frequency response and corresponding circularity coefficients. The display may be animated to allow a user to view the signal and/or filters in the frequency domain at different times.
    Type: Application
    Filed: March 31, 2017
    Publication date: October 12, 2017
    Inventors: John J. Pickerd, Kan Tan
  • Publication number: 20170168092
    Abstract: Embodiments of the present invention provide techniques and methods for improving signal-to-noise ratio (SNR) when averaging two or more data signals by finding a group delay between the signals and using it to calculate an averaged result. In one embodiment, a direct average of the signals is computed and phases are found for the direct average and each of the data signals. Phase differences are found between each signal and the direct average. The phase differences are then used to compensate the signals. Averaging the compensated signals provides a more accurate result than conventional averaging techniques. The disclosed techniques can be used for improving instrument accuracy while minimizing effects such as higher-frequency attenuation. For example, in one embodiment, the disclosed techniques may enable a real-time oscilloscope to take more accurate S parameter measurements.
    Type: Application
    Filed: April 29, 2016
    Publication date: June 15, 2017
    Inventors: Kan Tan, John J. Pickerd
  • Publication number: 20170089954
    Abstract: A test and measurement instrument, including a splitter configured to split an input signal into two split input signals and output each split input signal onto a separate path and a combiner configured to receive and combine an output of each path to reconstruct the input signal. Each path includes an amplifier configured to receive the split input signal and to compress the split input signal with a sigmoid function, a digitizer configured to digitize an output of the amplifier; and at least one processor configured to apply an inverse sigmoid function on the output of the digitizer.
    Type: Application
    Filed: September 30, 2015
    Publication date: March 30, 2017
    Inventors: John J. Pickerd, Kan Tan
  • Patent number: 9596074
    Abstract: Embodiments of the present invention provide improved techniques for recovering clock information from data signals. In one embodiment, a general purpose device such as a real-time oscilloscope acquires a data signal. The device takes a derivative of the data signal, then computes the square or absolute of the derivative before applying a bandpass filter. The bandpass filter is a windowing function a spectrum that is wider than the clock, and has a flat top and smooth transitions on both sides. In one embodiment, at Tukey window may be used. The device finds edge crossing times of the filtered result, and applies a phase-locked loop or lowpass filter to the edge crossing times in order to recover a stable clock signal. When the improved techniques are implemented in software, they may be used with any number of different equalizers that are required by various high-speed serial data link systems.
    Type: Grant
    Filed: March 21, 2016
    Date of Patent: March 14, 2017
    Assignee: Tektronix, Inc.
    Inventor: Kan Tan
  • Publication number: 20160323094
    Abstract: Embodiments of the present invention provide improved techniques for recovering clock information from data signals. In one embodiment, a general purpose device such as a real-time oscilloscope acquires a data signal. The device takes a derivative of the data signal, then computes the square or absolute of the derivative before applying a bandpass filter. The bandpass filter is a windowing function a spectrum that is wider than the clock, and has a flat top and smooth transitions on both sides. In one embodiment, at Tukey window may be used. The device finds edge crossing times of the filtered result, and applies a phase-locked loop or lowpass filter to the edge crossing times in order to recover a stable clock signal. When the improved techniques are implemented in software, they may be used with any number of different equalizers that are required by various high-speed serial data link systems.
    Type: Application
    Filed: March 21, 2016
    Publication date: November 3, 2016
    Inventor: Kan Tan