Patents by Inventor John F. Stoops

John F. Stoops 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).

  • Patent number: 9172362
    Abstract: A circuit includes a load; a first differential pair coupled to the load and responsive to input data; a second differential pair coupled to the load and responsive to the input data; a third differential pair coupled to the first differential pair and the second differential pair and responsive to a first control signal and a second control signal; a bias circuit configured to pull a node coupled to both the first differential pair and the second differential pair to a predetermined state; and a current source coupled to the third differential pair and the bias circuit.
    Type: Grant
    Filed: June 19, 2013
    Date of Patent: October 27, 2015
    Assignee: TEKTRONIX, INC.
    Inventors: John F. Stoops, Daniel G. Knierim
  • Publication number: 20130278291
    Abstract: A circuit includes a load; a first differential pair coupled to the load and responsive to input data; a second differential pair coupled to the load and responsive to the input data; a third differential pair coupled to the first differential pair and the second differential pair and responsive to a first control signal and a second control signal; a bias circuit configured to pull a node coupled to both the first differential pair and the second differential pair to a predetermined state; and a current source coupled to the third differential pair and the bias circuit.
    Type: Application
    Filed: June 19, 2013
    Publication date: October 24, 2013
    Inventors: John F. STOOPS, Daniel G. KNIERIM
  • Patent number: 8531209
    Abstract: A circuit includes a load; a first differential pair coupled to the load and responsive to input data; a second differential pair coupled to the load and responsive to the input data; a third differential pair coupled to the first differential pair and the second differential pair and responsive to a first control signal and a second control signal; a bias circuit configured to pull a node coupled to both the first differential pair and the second differential pair to a predetermined state; and a current source coupled to the third differential pair and the bias circuit.
    Type: Grant
    Filed: January 16, 2009
    Date of Patent: September 10, 2013
    Assignee: Tektronix, Inc.
    Inventors: John F. Stoops, Daniel G. Knierim
  • Publication number: 20100182048
    Abstract: A circuit includes a load; a first differential pair coupled to the load and responsive to input data; a second differential pair coupled to the load and responsive to the input data; a third differential pair coupled to the first differential pair and the second differential pair and responsive to a first control signal and a second control signal; a bias circuit configured to pull a node coupled to both the first differential pair and the second differential pair to a predetermined state; and a current source coupled to the third differential pair and the bias circuit.
    Type: Application
    Filed: January 16, 2009
    Publication date: July 22, 2010
    Applicant: Tektronix, Inc.
    Inventors: John F. STOOPS, Daniel G. KNIERIM
  • Patent number: 7068087
    Abstract: A method and apparatus for an improved timer circuit and improved pulse width detection includes initiating a ramp timer and setting a timer latch output level substantially simultaneously in response to the occurrence of an input signal. The occurrence of the input signal also causes a counter to be enabled to count clock cycles. The ramp timer signal of the ramp timer is frozen (i.e., paused) by a timer control circuit, upon the occurrence of a first clock cycle following the enabling of the counter. The counter then counts a predetermined number of clock cycles after the ramp timer signal is frozen and, upon the occurrence of a last one of a predetermined number of clock cycles, generates a terminal count signal. Upon receiving the terminal count signal, the timer control circuit unfreezes ramp timer signal. The ramp timer runs until completion at which time the ramp timer generates an end of ramp control signal. The control signal is communicated to timer latch to reset timer latch output level.
    Type: Grant
    Filed: February 24, 2004
    Date of Patent: June 27, 2006
    Assignee: Tektronix, Inc.
    Inventors: John F. Stoops, Steven K. Sullivan
  • Patent number: 6720828
    Abstract: A high impedance attenuator for use in a test and measurement instrument employs compensation to adjust the low frequency attenuation to match the high frequency attenuation exhibited by the attenuator, rather than attempting to adjust the high frequency attenuation exhibited by the attenuator. In an alternate embodiment of the invention, compensation to adjust low frequency attenuation is employed in a feedback loop and an opposite compensation is applied in a parallel attenuation stage to stabilize the input resistance. In yet another embodiment of the invention, compensation to adjust low frequency attenuation is employed by means of an R-C time constant of an additional R-C circuit in a feed forward loop. This additional time constant is matched to the R-C time constant of the input R-C network. The input resistance of the attenuator is not changed.
    Type: Grant
    Filed: November 21, 2001
    Date of Patent: April 13, 2004
    Assignee: Tektronix, Inc.
    Inventors: Theodore G. Nelson, Michael P. Khaw, Daniel G. Knierim, John F. Stoops
  • Patent number: 6614221
    Abstract: A deskew fixture has a multilayer circuit board from which pairs of mirrored signal launch contact extend from both sides of the circuit board. One pair of contacts is coupled to electrical ground and the other pair is connected via equal length, electromagnetically coupled strip lines to a signal source. Probe holders are mounted on the circuit boards to support measurement probes with the probing contacts of the measurement probes coupled to the signal launch contacts. Additional pairs of signal launch contacts may be provided with one pair receiving a positive signal from the signal source and another pair receiving a negative signal via equal length, electromagnetically coupled strip lines from the signal source for deskewing differential measurement probes.
    Type: Grant
    Filed: May 17, 2002
    Date of Patent: September 2, 2003
    Assignee: Tektronix, Inc.
    Inventors: Kelly F. Cushing, Mark W. Nightingale, John F. Stoops, John C. Calvin, Marc A. Gessford, Marie Ottum
  • Publication number: 20030128023
    Abstract: A deskew fixture has a multilayer circuit board from which pairs of mirrored signal launch contact extend from both sides of the circuit board. One pair of contacts is coupled to electrical ground and the other pair is connected via equal length, electromagnetically coupled strip lines to a signal source. Probe holders are mounted on the circuit boards to support measurement probes with the probing contacts of the measurement probes coupled to the signal launch contacts. Additional pairs of signal launch contacts may be provided with one pair receiving a positive signal from the signal source and another pair receiving a negative signal via equal length, electromagnetically coupled strip lines from the signal source for deskewing differential measurement probes.
    Type: Application
    Filed: May 17, 2002
    Publication date: July 10, 2003
    Inventors: Kelly F. Cushing, Mark W. Nightingale, John F. Stoops, John C. Calvin, Marc A. Gessford, Marie Ottum
  • Publication number: 20030102913
    Abstract: A high impedance attenuator for use in a test and measurement instrument employs compensation to adjust the low frequency attenuation to match the high frequency attenuation exhibited by the attenuator, rather than attempting to adjust the high frequency attenuation exhibited by the attenuator. In an alternate embodiment of the invention, compensation to adjust low frequency attenuation is employed in a feedback loop and an opposite compensation is applied in a parallel attenuation stage to stabilize the input resistance. In yet another embodiment of the invention, compensation to adjust low frequency attenuation is employed by means of an R-C time constant of an additional R-C circuit in a feed forward loop. This additional time constant is matched to the R-C time constant of the input R-C network. The input resistance of the attenuator is not changed.
    Type: Application
    Filed: November 21, 2001
    Publication date: June 5, 2003
    Inventors: Theodore G. Nelson, Michael P. Khaw, Daniel G. Knierim, John F. Stoops
  • Patent number: 5841286
    Abstract: An oscilloscope comprises a trigger circuit for initiating display of the waveform of an input signal in response to a trigger event, at least one detection circuit responsive to the input signal for detecting occurrence of an anomalous event therein, and a counter for reporting the number of occurrences of the anomalous event that have been detected.
    Type: Grant
    Filed: February 17, 1995
    Date of Patent: November 24, 1998
    Assignee: Tektronix, Inc.
    Inventor: John F. Stoops
  • Patent number: 4873646
    Abstract: An M-element waveform data sequence representative of an analog input signal during a period of interest is produced by first amplifying the input signal with a linear amplifier and periodically digitizing the amplifier output signal to produce a first data sequence having M+N-1 elements. The first N-1 elements of the first data sequence represent magnitudes of the amplifier output signal preceding the period of interest, and the remaining M elements of the first data sequence represent magnitudes of the amplifier output signal during the period of interest. The first data sequence is applied as input to a digital filter which produces an output second data sequence wherein each element of the second data sequence corresponds to an element of the first data sequence and is a linear combination of its corresponding first data sequence element and N-1 data preceding data elements of the first data sequence.
    Type: Grant
    Filed: January 4, 1988
    Date of Patent: October 10, 1989
    Assignee: Tektronix, Inc.
    Inventor: John F. Stoops
  • Patent number: 4808858
    Abstract: A current signal limiter provides precise minimum and maximum current limiting. Both maximum and minimum current limits are easily programmable. The signal limiter operates at maximum frequency response without inversion of the input signal. Current signal limiting is achieved by an NPN transistor biased in a common base configuration with the base coupled to a reference voltage source and the collector providing the output current, a series diode coupled to the emitter of the transistor for receiving a trickle current which prevents the transistor from turning off as well as setting a minimum current limit, and a diode matrix for receiving two reference currents and an input current. The diode matrix steers the input and reference currents to the transistor or to the reference voltage source, depending on the magnitude of the input and reference currents. The minimum and maximum current limits are programmable by adjusting the values of the reference currents and the trickle current.
    Type: Grant
    Filed: January 25, 1988
    Date of Patent: February 28, 1989
    Assignee: Tektronix, Inc.
    Inventor: John F. Stoops