Tyler Ross

Design of X-Band GaN Phase Shifters

This paper presents two different types of high-power gallium-nitride (GaN) phase shifters designed for X-band (8-12 GHz), but offering good performance over a much wider band. The first is a 22.5° switched-filter phase shifter, which has much wider bandwidth than is typically found with this configuration, while maintaining low insertion loss (<; 2 dB), good return loss ( >11.15 dB), and an amplitude imbalance of less than 1.03 dB across X-band. The 1-dB compression point was higher than laboratory equipment was able to measure ( >38 dBm) and the phase shifter monolithic microwave integrated circuit exhibited an input-referred third-order intercept point (IIP3) of 46.2 dBm. The second phase shifter is a novel design, which promises wide bandwidth (in our case, limited by the single-pole double-throw switch we have also designed), but which achieves decent insertion loss (5 dB), good return loss (better than 11 dB), and very low phase variation (1°) across X-band, also with 22.5° phase shift. It offers a 1-dB compression point of 30.1 dBm and an IIP3 of 46.3 dBm. The components for a 45 ° differential phase shift using the same structure were also fabricated and verified with measurements. The high-power phase shifters have been fabricated in a 0.5- μm GaN HEMT process and were designed using an accurate customized switch field-effect transistor model.

A new type of GaN HEMT based high power high-pass/low-pass phase shifter at X band

This paper presents a new type of robust GaN HEMT-based high power phase shifter operating at X-band. The proposed 0°/45° high-pass/low-pass phase shifter exhibits low insertion loss (2.5 dB), good return loss, and amplitude variation lower than 0.5 dB for the two phase states over the entire operational bandwidth ranging from 6 to 13 GHz. The relative phase performance is fairly constant over the bandwidth. The proposed phase shifter MMIC has been successfully demonstrated using a 0.8 µm gate GaN HEMT process.

High-power X-band GaN switched-filter phase shifter

This paper presents a high-power switched-filter GaN phase shifter, designed for X-band and offering good performance from 8-16 GHz. The manufactured 0°/22.5° switched-filter phase shifter has much wider bandwidth than is typically found with this configuration, while maintaining low insertion loss (<; 2 dB), good return loss (> 11.15 dB) and an amplitude imbalance of less than 1.03 dB across X-band. The 1 dB compression point was higher than laboratory equipment was able to measure (> 38 dBm) and the phase shifter MMIC exhibited an IIP3 higher than 46 dBm. The proposed high-power phase shifter has been fabricated in a 0.5 μm GaN HEMT process and was designed using an accurate, customized switch FET model.

Particle swarm optimization for ellipsometric data inversion of samples having an arbitrary number of layers

A method is presented for performing the inversion of ellipsometric data using a hybrid approach involving a particle swarm optimization algorithm and a Levenberg-Marquardt algorithm. A sample may be composed of any number of layers of transparent or absorbing materials on a substrate. The method described is applicable to single- or multiple-angle, single-wavelength ellipsometry. The results of the particle swarm optimization algorithm agree well with previously published data calculated using different ellipsometric inversion algorithms, and converges for wide ranges of initial parameter estimates.

Low-cost mm-wave coplanar waveguide bandpass filter using inkjet printing of silver nano-particles on flexible plastic substrate

This paper demonstrates the feasibility of realizing millimeter wave coplanar waveguide (CPW) bandpass filters through ink-jetting of conductive inks on commercially available plastic sheets such as Polyethylene Terephthalate (PET) (plastic as an RF substrate). A silver nanoparticle colloidal solution was used as the printing ink. The millimeter wave third order CPW bandpass filter, which consists of a cascade of alternating quarter wavelength CPW open end series stubs and quarter wavelength CPW connecting lines, was simulated with Agilent Momentum and printed with a DMP-2800 Series inkjet printing system. The principle of achieving such high-quality circuits is detailed and is also confirmed by theoretical and experimental results, which are in reasonable agreement up to at least 70 GHz. Finally, this work is one step further towards the development of low-cost ink-jet printing of passive microwave and millimeter-wave components for commercial wireless applications.

DC to 70 GHz 90 nm 3D CMOS SPDT using elevated CPW and CPS series stubs

This paper proposes a new approach for realizing a compact SPDT switch incorporating compact, elevated coplanar waveguide (ECPW) series stubs in conjunction with CPS series stubs in order to extend the operating frequency. The design technique has been successfully demonstrated using a multi-layer 90nm CMOS process. The proposed SPDT switch takes advantage of the multi-level metallization processes offered in CMOS technology. The intrinsic area of the fabricated 3D SPDT switch is significantly reduced. Simulated and experimental results are presented in support of the novel compact switch. The switch achieves a measured insertion loss of less than 3.8 dB and a measured isolation of better than 18 dB from DC to 70 GHz.

Frequency Domain Phase Shift Measurement Technique Applied to a Multiphase Rotary Travelling-Wave VCO

In this letter, the design of a multiphase 18.5 GHz Rotary Travelling-Wave Oscillator (RTWO) is presented. Lack of symmetry in such a structure can result in oscillation in a standing wave rather than the travelling wave mode. In order to determine the mode of the signal, before going through the time consuming steps of time domain phase shift measurement, we have proposed a preliminary phase shift measurement technique in the frequency domain for a high frequency RTWO. This new technique was verified against direct phase measurements for a multiphase RTWO fabricated in a 0.25 μm BiCMOS process with good agreement. In other measurements, the VCO achieved a tuning range of 1.1 GHz and output power of -5.3 dBm.

Development of a Model for a Microwave GaInP\/GaAs HBT

This article presents the development of a nonlinear model for a microwave gallium indium phosphide (GaInP)/gallium arsenide (GaAs) heterojunction bipolar transistor (HBT). This model tied for first prize in the Microwave Transistor Modeling student competition held during the 2014 IEEE Microwave Theory and Techniques Society International Microwave Symposium (IMS2014) in Tampa, Florida.

Extraction of a Model for a Microwave Power pHEMT

This article presents the development of a large-signal transistor model for a power microwave pseudomorphic high-electron mobility transistor (pHEMT). This model won the first prize in the Microwave Transistor Modeling student competition held during the 2013 IEEE Microwave Theory and Techniques Society (MTT-S) International Microwave Symposium (IMS2013) in Seattle, Washington.

Miniature single-sideband subharmonically-pumped 60 GHz direct upconverter in a uniplanar GaAs pHEMT technology using inductive and capacitive loading techniques

This paper presents a novel, compact, single-sideband (SSB) subharmonically-pumped (SHP) direct upconverter developed in a uniplanar 0.18 mu m GaAs technology. A total of 100 MHz in-phase and quadrature signals directly modulate the second harmonic of a 30 GHz carrier signal, producing a 60.1 GHz output. Two pairs of antiparallel diodes reduce feed-through of the 30 GHz local oscillator (LO) signal to the mixers RF output. Novel structures patterned in the center conductor of a coplanar waveguide (CPW) provide matching and size-reduction simultaneously. The 2.1mm(2) circuit also uses a miniaturized Wilkinson divider based on asymmetric coplanar stripline and a standard CPW 90 degrees coupler. The SSB SHP direct upconverter exhibits a conversion loss of 10 dB, a lower-sideband rejection of 15 dB and 2f(LO) suppression of approximately 25 dB over a wide frequency range from 52-61 GHz.