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The 2013 International Microwave Symposium (IMS) is annually the largest gathering of RF/microwave professionals in the world.
ARFTG Tackles High-Speed Testing
Seattle is also home to the 81st Automatic RF Techniques Group (ARFTG) conference I 2013, scheduled for the last day of Microwave Week (June 7, 2013). The theme of this ARFTG meeting is “Metrology for High Speed Circuits and Systems,” organized into four groups of oral presentations during the day starting at 8 AM. ARFTG has long been a special day at each IMS for test engineers and for anyone seeking to learn more about high-frequency measurements.
The ARFTG oral presentations are accompanied by a miniature version of the IMS exhibition hall, with little booths for each sponsor to show one or two test solutions to attendees. Sponsors for this miniature ARFTG exhibition include Agilent Technologies, Anritsu Co., Electro Rent Corp., Focus Microwaves, Maury Microwave, and RFMD.
The opening oral presentation, by Nick Ridler of the National Physics Laboratory (NPL) in Teddington, England, investigates primary standards of loss for vector network analyzers (VNAs) operating at millimeter-wave frequencies and higher. The standards under study are known as “cross-connected” waveguide; these are straight sections of waveguide, where the waveguide line is oriented such that the waveguide aperture is at right angles to the waveguide apertures on the VNA’s test ports. The cross-cross connected waveguide forms a section of transmission line that is effectively below cutoff. The mechanical discontinuity between the cross-connected waveguide and the VNA test ports also generates significant reflection. Understanding these two loss mechanisms is critical to performing accurate VNA measurements at millimeter-wave and sub-millimeter-wave frequencies.
The opening ARFTG oral session includes a talk on calibrating multi-channel test probes by presenters from Cascade Microtech (Beaverton, OR) and Microsemi (Bend, OR), as well as a unique wideband calibration procedure for systems performing time-domain measurements on nonlinear devices. Offered by presenters from the University of Limoges in Limoges CEDEX, France, this latter presentation details a calibration method based on the use of a wideband, multiple-sine wave signal that is applied to a measurement setup using a four-channel track-and-hold amplifier. The system was used to demonstrate measurements on a 40-W GaN power amplifier driven by a pulsed input signal.
The second ARFTG oral session returns to the topic of waveguide calibration and VNAs, as presenters from the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan compare waveguide VNA systems calibrated by means of through-reflect-line (TRL) calibrations with different lengths of line. The systems are being used for measurements in the WM-250 (WR-1.0) frequency band from 750 GHz to 1.1 THz.
The calibration employs a new waveguide flange design for precise connections, investigating whether the TRL calibration approach is suitably accurate for VNA measurements at THz frequencies. Additional presentations in the second session cover phase-noise measurements on low-noise oscillators, a field probe for amplitude measurements, and error corrections for pulsed S-parameter measurements. Additional oral sessions offer coverage of active harmonic load-pull measurements at Ka-band frequencies, the use of comb generators for modulated measurements, figures of uncertainty for noise-figure measurements, and the impact of test cable instability on the accuracy of VNA measurements.
RFICs Range From HF To Millimeter Waves
Integrated-circuit (IC) designers and users will find three days of their own at the 2013 Microwave Week in Seattle, as part of the 2013 IEEE RFIC Symposium. Scheduled for June 2-4 also at the Washington State Convention Center, the RFIC Symposium opens the 2013 Microwave Week with presentations, workshops, tutorial lessons, and even an evening reception after the first day of sessions.
The General Chairperson for the 2013 RFIC Symposium is Chris Rudell, from the Electrical Engineering Department at the University of Washington in Seattle. For those interested in a broad spectrum of RFICs, as well as the technologies with which they are fabricated (such as GaAs, GaN, and silicon), the technical program features sessions on high-speed data transceivers, low-power transceivers, front-end circuits, voltage-controlled oscillators (VCOs), frequency control circuits, millimeter-wave systems on a chip (SOCs), and modeling and computer-aided design (CAD).
As an example of one presentation, lecturers from the University of Washington and Avago Technologies will detail their design of a 1.9-GHz oscillator using a phase-noise-reduction technique. Based on a high-quality factor (high-Q) film-bulk-acoustic-resonator (FBAR)/MEMS/crystal architecture, the oscillator signals are frequency-upconverted to 1.9 GHz. Nevertheless, the upconversion approach suppresses the 1/f noise via amplitude-modulation/phase-modulation (AM/PM) conversion, adding a nonlinear capacitor to the oscillator tank circuit.
The proposed AM-PM suppression technique has no additional power penalty and suffers minimal additional volume requirements. By applying the technique, a 1.9-GHz FBAR oscillator was developed with phase noise of -116 dBc/Hz offset 10 kHz from the carrier and -146 dBc/Hz offset 1 MHz from the carrier.