Tektronix, Inc.

John E Carlson

Michael Nelson

Agoston Agoston

John B Rettig

Stanley P Kaveckis

Jonathan C Lueker

Roy W Lewallen

Andrew E Finkbeiner

David J McCormick

Joan Mercade

Aspects of the invention include an equivalent-time sampling oscilloscope that receives a carrier signal, the carrier signal after it has been modulated with a repeating data pattern, and a pattern trigger signal that is synchronous with the data pattern. The carrier signal and the modulation are asynchronous, that is, they are not phase-locked in any way. The oscilloscope simultaneously samples the modulated carrier signal and quadrature phases of the unmodulated carrier signal at a plurality of timebase delays relative to the pattern trigger signal, and a plurality of times at each timebase delay. After collecting this information, the oscilloscope uses the quadrature samples to calculate phases of the unmodulated carrier signal that correspond to the samples of the modulated carrier signal. The oscilloscope then calculates a stationary representation of the modulated carrier signal by selecting samples of the modulated carrier signal that correspond to a carrier signal phase progression that would have been observed if the unmodulated carrier signal had been synchronous with the pattern trigger signal.

Equivalent-time sampling technique for non-coherently modulated signals

Waveforms generators include a splitter that splits a digital input signal into a number of split signals each having a split signal frequency bandwidth that is substantially similar to a digital input signal frequency bandwidth. The split signals are mixed with associated digital, harmonic signals to generate a number of digital, mixed signals, which are then converted to analog signals at an effective sample rate that is different from a first order harmonic signal of at least one of the digital, harmonic mixers. A number of analog, harmonic mixers mix the associated analog signals with associated analog, harmonic signals to generate mixed, analog signals. The mixed, analog signals are combined into an output signal having an output signal bandwidth that is greater than a bandwidth of at least one of the number of DACs.

Asynchronous time-interleaved waveform generator using harmonic mixing

A method of producing of a two-dimensional probability density function eye diagram and Bit Error Rate eye arrays generates a two-dimensional PDF array of a correlated waveform record of a data pattern under test which is convolved with a two-dimensional probability density function (PDF) array of the uncorrelated jitter and noise in the data pattern under test. The resulting aggregate two dimensional PDF array of the correlated waveform record pattern with uncorrelated jitter and noise is divided into unit intervals and the unit intervals are summed to generated a two-dimensional PDF eye diagram array. The two-dimensional PDF eye diagram is processed to generate a two-dimensional Bit Error Rate eye array.

Method of producing a two-dimensional probability density function (PDF) eye diagram and Bit Error Rate eye arrays

A reference receiver has a biased, strobed sampling system that is tuned to provide the predominant frequency response of the reference receiver allowing for the removal of the discrete reference receiver filter. The reference receiver has a photodiode optical-to-electrical converter that is configured to effectively utilize the current output of the high impedance source in that the converter is not reverse terminated to the characteristic impedance of a transmission coupled to the electrical output of the converter. The electrical output of the converter is coupled to a sampling circuit that receives biasing voltages and gating strobe pulses for producing an approximate Bessel-Thompson filter response from the sampling circuit. The combination of the unterminated optical-to-electrical converter and the tuned sampling circuit results in a reference receiver having higher gain and narrower reference receiver tolerance limits.

Discrete filter-less optical reference receiver and output amplifier

An output amplifier for a strobed sampling circuit has first and second operational amplifiers coupled to receive the sampled output from the sampling circuit. The operational amplifiers each have a RC circuit having a high ohmic value resistor that is coupled from its inverting input terminal to its output terminal. The non-inverting input terminals receive biasing voltages that are coupled to the sampling circuit. The gating strobes to the sampling circuit produces a DC current through the feedback resistor as a result of strobe pulses being integrated by the RC circuit. Respective electronic switches are coupled in parallel with the RC circuits of the operational amplifiers and are closed at a predetermined time interval after each strobe pulse to discharge the stored charge on the capacitors prior to the next strobe pulse. The output signals from the operational amplifiers are summed in a summing amplifier.

Output amplifier for a discrete filter-less optical reference receiver

A step generator for producing steps having constant edge parameters while driving varying loads includes a pair of DC coupled low speed diode switches for slowly switching the output load current. A pair of capacitors provide an AC coupled high speed input for rapidly, but temporarily, switching the output load current until the sustaining action of the low speed diode switch has occurred. A pair of resistor divider circuits in each of the low speed diode switches maintains a relatively constant reverse bias voltage across the diodes coupled to the capacitors. The high speed switching threshold is maintained at a relatively constant level which produces an output voltage step with constant edge parameters and no overshoot.

High speed step generator output circuit

A pulse generator utilizes a pair of current sources acting through a pair of Schottky diode switches to provide load currents in opposite directions through a load resistor to produce an output voltage across the load resistor of magnitude proportional to the difference between the load current magnitudes. The pulse generator output voltage is abruptly driven to zero potential by applying balanced, rapid slewing voltage pulses to the Schottky diode switches, causing the switches to simultaneously divert the load currents from the load resistor. The balanced voltage pulses are developed at the terminals of a step-recovery diode by switching the step-recovery diode from forward to reverse bias state.

Fast transition, flat pulse generator

A dual channel time domain reflectometer includes a pair of input lines connected at respective nodes to a reference flat current pulse generator and a traveling wave sampling gate, respectively. The sampling gates are actuated by a balanced strobe generator which includes a waveguide coupler for coupling a high amplitude fast rise time pulse to each of the gates simultaneously. Pulses of requisite amplitude and shape are generated by a circuit responsive to a strobe trigger input which drives a step recovery diode.

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Portland, OR, United States of America

John E Carlson