Efficient generation of X-parameters transistor models by sequential sampling

This letter proposes a sequential sampling technique to generate efficiently multidimensional X-parameters models for microwave transistors, while guaranteeing X-parameters' validity and overcoming simulator convergence issues. The sequential sampling process selects a set of samples that are subsequently used to construct behavioral models with radial basis functions. The proposed method was compared with a tabular X-parameters model with cubic spline interpolation. The radial basis function models demonstrate very fast convergence and greater accuracy already for a few tens of samples. The proposed technique is illustrated for a GaAs HEMT using Curtice3 and Chalmers empirical model simulations as the data source

Hybrid nonlinear modeling using adaptive sampling

This paper proposes a direct method for the extraction of empirical-behavioral hybrid models using adaptive sampling. The empirical base is responsible for the functionality over a wide range of variables, especially in the extrapolation range. The behavioral part corrects the errors of the empirical part in the region of particular interest, thus, it improves the accuracy in the desired region. Employment of response surface methodology and adaptive sampling allows full automation of the hybrid model extraction and assures its compactness. We used this approach to build a hybrid model composed of a robust empirical model available in CAD tools and a Radial Basis Functions interpolation model with Gaussian basis function. We extracted the hybrid model from measurements of a 0.15 mu m GaAs HEMT and compared it with the pure behavioral and pure empirical models. The hybrid model yields higher accuracy while maintaining extrapolation capabilities. Additionally, the extraction time of the hybrid model is relatively low. We also show that a good accuracy level can be achieved with a small number of measurements

Phase-Error Compensation of a Pulsed Power Amplifier with a Vector Modulator in Radar Applications

This paper describes a phase-error compensation method employing the digital predistortion for pulsed power amplifiers in radar applications. The predistortion method was evaluated for the power amplifier based on the commercially available Avago ATF52189 HEMT at frequency 1.3 GHz. The measurement setup and the extraction procedure of the inverse model of the power-amplifier phase distortion is presented. Using proposed method the maximum phase-error was reduced from 5° to 0.8°, while the gain changes only within 0.1 dB.status: publishe

Offset-Shorts Vector-Network-Analyzer Calibration with Simultaneous Modeling of Calibration Standards

We present an improved offset-short vector-network-analyzer calibration method which allows to identify broadband equivalent-circuit models of the offset-short standards and an imperfect thru connection. Our approach is based on the multi-frequency formulation of the vector-network-analyzer calibration problem in which parameters of the models are identified simultaneously with the vector-network-analyzer calibration coefficients at all frequencies. Thus, the impact of the constraints imposed by the models is also reflected in the calibration coefficients. We illustrate our approach with experimental results for an offset-short calibration in coaxial 3.5 mm connector. These results demonstrate that our method reduces the impact of measurement errors, and extends the bandwidth of the calibration.status: publishe

GPU Implementation of Multiline TRL Calibration for Efficient Monte-Carlo Uncertainty Analysis

We present a graphics-processing-unit (GPU) OpenCL implementation of the multiline through-reflect-line (TRL) algorithm of vector-network-analyzer (VNA) calibration. We obtained about 40× of speed improvement on a middle-end GPU as compared to a single-threaded C/C++ implementation. This speed improvement leads to a significant acceleration of VNA-measurement Monte-Carlo uncertainty analysis, making it possible to evaluate VNA measurement uncertainties in a timeframe of a few minutes.status: publishe

A Transmission Line Based Microwave Heater at 25 GHz for Continuous Flow Microfluidics Fabricated on Silicon

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Small-signal microwave measurements and modeling of GaN FET devices manufactured by ITME

© 2015, Kluwer Academic Publishers. All Rights Reserved. We present results of small-signal measurements and modeling of GaN FET devices  anufactured by Institute of Electronics Materials Technology (ITME). The devices have 500 nm gate length and 100 μm gate width and are grown on 350 μm sapphire substrate. We measured scattering parameters of the devices on-wafer in the frequency range 0.01-15 GHz, and then extracted parameters of their small-signal equivalent circuits. These results show that the devices have repeatable parameters and are capable of delivering at least 14.4 dB of unilateral gain in S-band with fmax of at least 23 GHz.status: publishe

Hybrid nonlinear model for microwave active devices using kriging

This paper presents a hybrid empirical-behavioral model applied to microwave active devices. The empirical part ensures meaningful, physical response over a wide range of variables, while the behavioral part boosts the accuracy in the particular region of interest. A simple Kriging with zero mean value is employed as the behavioral model. Such hybrid model outperforms the sole empirical model and a hybrid with radial-basis-functions model both in interpolation performance and lower extraction time. The extrapolation capabilities of the model are maintained