Tektronix, Inc.

Picosecond Pulse Labs

Tetronix, Inc.

Steven H Pepper

John Ebner

Agoston Agoston

Mihir K Ravel

Robert Norton

David W Pratt

Jeffrey H Goll

Bozidar Janko

Michael D Jones

R Clayton Smith

Ralph T Hawkins, Ii

Stephen P Jachim

Ronald L Ramsey

Scott K Diamond

James R Andrews

John T Ebner

Frequency converters include waveguides configured for a local oscillator (LO) signal, an intermediate frequency (IF) signal, and an RF signal. A multimode IF waveguide can be used for selectively coupling of an IF signal and to reduce signal contributions produced by the LO signal. Typically, the multimode waveguide is situated to that the IF signal and the LO signal propagate in different waveguide modes, and a selected one of these signals can be selectively attenuated. In some examples, a periodically stepped waveguide is used to enhance propagation of a selected waveguide mode or a lossy conductor is used to attenuate a selected waveguide mode.

Waveguide samplers and frequency converters

Comb generators include a nonlinear transmission line (NLTL) having one or more NLTL sections. Each NLTL section includes one or more nonlinear elements and transmission line portions that provide transmission line dispersion. Typically, the nonlinear elements are Schottky diodes, and a pulse forming bias network is configured to establish Schottky diode bias conditions using a periodic signal that is input to the comb generator. For input periodic signals at frequencies between about 500 MHz and 1 GHz, output signals are produced having substantial power in frequency components at frequencies up to at least about 50 GHz.

Biased nonlinear transmission line comb generators

An ultrafast sampler includes a series of Schottky diodes configured with a coplanar waveguide to form a nonlinear transmission line (NLTL) that compresses a local oscillator input to form a series of strobe pulses. Strobe pulses of opposite polarity are capacitively coupled to sampling diodes to obtain samples of a signal applied to a signal input. The samples are directed along an intermediate frequency waveguide to, for example, a signal processor such as an oscilloscope, for storage and analysis. The intermediate frequency waveguide is configured so that conductors of the intermediate frequency waveguide receive signal samples of a common polarity and strobe samples of opposite polarities so that portions of strobe pulses delivered to a signal processor are distinguished from signal samples. In an embodiment, the intermediate frequency waveguide and the strobe waveguide are symmetrically situated along a common axis, and conductors of the strobe waveguide are positioned between the axis and the conductors of the intermediate frequency waveguide. The sampling circuit is defined on a GaAs substrate and a coaxial-to-airline-to-substrate transition is configured to deliver signals from a coaxial cable to the sampling circuit. A signal output is configured to direct the signal back into a coaxial cable.

Ultrafast sampler with coaxial transition

Waveguide nonlinear signal processors include transmission lines defined on a substrate. A plurality of varactors or pairs of varactors are situated along the transmission line and are in communication with a signal conductor of the transmission line and one or more control conductors. A processor controller is configured to provide a control signal to the one or more control conductors to select operational characteristics of the varactors or pairs of varactors. In some examples, the varactors are diodes and a control signal is provided to select a diode current-voltage characteristic in order to limit or clip an input signal to positive and/or negative amplitudes. Alternatively, a control signal is configured to provide a selected spectral transmission bandwidth or propagation delay by selecting a varactor capacitance-voltage characteristic.

Transmission line voltage controlled nonlinear signal processors

An ultrafast sampling system includes an interposer and a sampler that include series of Schottky diodes configured with a non-parallel waveguide to form shocklines or nonlinear transmission line (NLTLs) that produce a differential strobe pulse. The shocklines are defined by non-parallel conductors that are configured as, for example, triangular, dentate, arcuate, or other shapes, or as conductors that have edges that are triangular, dentate, arcuate, or the like. The conductors are defined with respect to a substrate, and are airbridged so that at least some portions of the conductors are displaced from the substrate to reduce waveguide capacitance. Electrical connection to the sampler is made with airline having a inner conductor that is deformable to contact an input pad defined on the sampler.

Ultrafast sampler with non-parallel shockline

A multi-octave, wideband voltage controlled oscillator has a plurality of high impedance current output individual voltage controlled oscillators coupled in parallel to form a bank of voltage controlled oscillators covering at least one high frequency octave. The outputs of the VCOs are wire-OR'd together and the VCOs are selected by a select signal that turns on the desired oscillator(s). A main limiter/divider selects a frequency octave at either the fundamental frequency of the selected VCO or a sub-harmonic thereof as the multi-octave, wideband voltage controlled oscillator output. A reference limiter/divider selects a reference frequency from the selected VCO for use in a phase locked loop. Each VCO has a tank circuit coupled across the bases of a pair of transistors, the emitters of which are coupled through respective current sources to ground. The collectors of the transistors are coupled to the wire-OR'd network. A summer/subtracting circuit may be added at the output of the VCOs or at the inputs of the limiter/dividers so that either the fundamental or second harmonic frequency of the selected VCO is selected.

Multi-octave wideband voltage controlled oscillator

A bandpass sampling system ( ) of this invention employs a conventional mixer ( ) driven by a frequency-tunable LO ( ) to upconvert a signal frequency band to an IF frequency band that is above the signal frequency band. The IF frequency band is passed through an IF bandpass filter ( ) to provide to subsequent digitization stages ( ) an IF bandpass range of signal frequency components. In this architecture, the IF bandpass filter acts as an anti-alias filter for the digitization stages. The LO frequency is selected to place the upconverted signal frequency band within the pass band of the IF bandpass filter. The resultant IF bandpass signal is sampled and digitized at a rate that is commensurate with the IF bandwidth, but typically much lower than the IF bandpass center frequency. Signal sampling is carried out by a sample-and-hold or a track-and-hold circuit ( ), the output of which is applied to an ADC ( ) that is clocked ( ) at the same rate as the sampling circuit.

Bandpass sampling architecture for wide-frequency band signal analysis

A time-interleaved method for efficient operation of an acoustic wave sensor array couples each sensor repetitively and one at a time via a digitally-addressable analog switch, or multiplexer, to a single oscillator driver to form an oscillation circuit. A frequency of oscillation for each acoustic wave sensor is determined. The frequency for each acoustic wave sensor then is converted into a measurement value for the parameter to which each acoustic wave sensor is sensitive.

Time-interleaved method for efficient operation of an acoustic wave

An optical power conversion circuit converts an optical energy signal from an optical source, such as a laser diode, to a regulated D.C. electrical voltage using a single photodetector. A buck-boost circuit uses electrical current from the photodetector in response to the optical energy signal to store energy in an inductor during one polarity of a control signal, and transfers the energy from the inductor to an output capacitor during the other polarity of the control signal. The duty cycle of the control signal determines the regulated D.C. electrical voltage. A switch drive circuit generates the control signal as a pulse width modulated signal from the regulated D.C. electrical voltage and a reference voltage. The control signal is A.C. coupled to a pair of FET switches in the buck-boost circuit to alternately energize and charge the inductor and capacitor respectively. A switched capacitor is coupled in parallel with the photodetector to store energy from the photodetector when the inductor is transferring energy to the output capacitor. At startup one of the FET switches in the buck-boost circuit is normally closed and the other normally open, and a third FET switch decouples the switched capacitor from the photodetector. A startup modulation signal is generated at the optical source to provide switching action equivalent to that of the FET switches in the buck-boost circuit until the regulated D.C. voltage achieves a sufficient level to energize the switch drive circuit and sustain normal operation. A data pickoff circuit is inserted in series with the photodetector to retrieve a data signal impressed upon the optical energy signal without disturbing the D.C. content.

Optical power conversion

An optical module for an optically based measurement system, such as an electro-optic system (10) for measuring electrical characteristics of a device under test (14), has a probe arm (26), a layer of electro-optic material (27), and a first optical system for delivering a measurement beam (44) to the layer and for producing therefrom an information-carrying beam having optical characteristics indicative of the electric characteristics. The first optical system includes a first lens (128), and (optional) polarization bias adjustment (130), a dichroic beamsplitter (112), and a second lens (114). The module also has a second optical system for delivering an observation beam (66) through the layer and onto a portion (68) of the device and for forming from rays (69) stemming from the observation beam a light pattern (70) indicative of the portion. The information-carrying beam is analyzed in a polarization analysis module into component beams (136, 138) in respective linearly independent polarization states. Converters (144, 146) produce electrical signals (147, 148) indicative of the intensity of the respective component beams; alternatively, the component beams are conveyed for analysis elsewhere. Connections (46, 65, 74, 149, 150) to and from the components fixedly mounted relative to the probe arm are flexible, allowing the probe arm and the components to move freely in any direction relative to the device under test.

Optical module for an optically based measurement system

A temperature control system for acoustic wave chemical sensors monitors the frequency output from a reference sensor packaged within a heat conductive case with a test sensor. Since the frequency output fluctuates as a function of temperature, variations in frequency from a nominal value representing a desired steady state temperature for the sensors are detected and used as a control signal for a heating element attached to the heat conductive case.

Temperature control for chemical sensors

An inverse scattering processing method with enhanced noise immunity and resolution capabilities for use in modeling multi-layer acoustic, electromagnetic or other propagating media. A time bounded filtering step is incorporated within a peeling method for use in processing TDR characteristic waveforms of the propagating media.

Reduced noise sensitivity in inverse scattering through filtering

An automatic gain control circuit for an interferometer or a phase sensitive detector reduces sensitivity to fluctuations in amplitude of input signals. A pair of currents from the phase sensitive detector that represents a detected phase difference are input to an automatic gain control ratio detector. The output of the automatic gain control ratio detector is a function of the ratio of the difference and sum of the phase sensitive detector currents that is substantially independent of intensity or amplitude fluctuations of the input signals.

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Portland, OR, United States of America

Steven H Pepper