RSS-based indoor localization system with single base station

The paper proposes an Indoor Localization System (ILS) which uses only one fixed Base Station (BS) with simple non-reconfigurable antennas. The proposed algorithm measures Received Signal Strength (RSS) and maps it to the location in the room by estimating signal strength of a direct line of sight (LOS) signal and signal of the first order reflection from the wall. The algorithm is evaluated through both simulations and empirical measurements in a furnished open space office, sampling 21 different locations in the room. It is demonstrated the system can identify user’s real-time location with a maximum estimation error below 0.7 m for 80% confidence Cumulative Distribution Function (CDF) user level, demonstrating the ability to accurately estimate the receiver’s location within the room. The system is intended as a cost-efficient indoor localization technique, offering simplicity and easy integration with existing wireless communication systems. Unlike comparable single base station localization techniques, the proposed system does not require beam scanning, offering stable communication capacity while performing the localization process

A Non-Quasi-Static FET Model Extraction Procedure Using the Dynamic-Bias Technique

We extend the recently proposed dynamic-bias measurement technique to the identification of non-quasi-static FET models. In particular, we propose to exploit two high-frequency tickles superimposed on the low-frequency large-signal excitation. The tickle frequencies are chosen in order to separately extract the quasi-static and non-quasi-static model parameters. As case study, we extracted and validated the model of an GaAs pHEMT

Dynamic-Bias S-Parameters: A New Measurement Technique for Microwave Transistors

We present the first application of the recently introduced dynamic-bias measurement to the acquisition of the scattering (S-) parameters of microwave transistors under large-signal operating conditions. We demonstrate that by properly acquiring and processing dynamic-bias measurements, one can derive the S-parameters of a nonlinear device-under test across a time-varying large-signal operating point (LSOP). Interestingly, these time-varying S-parameters can be used similar to the conventional S-parameters for characterization and modeling purposes. As compared with similar existing approaches, like those based on the pulsed S-parameter measurements, with the proposed technique, one can obtain, as a result of one measurement, the frequency-dependent S-parameters at each instantaneous point touched by the LSOP. We report experimental dynamic-bias S-parameters of a 0.15-μm GaAs pHEMT and a 0.25-μm GaN HEMT

Effects of Gate-Length Scaling on Microwave MOSFET Performance

This paper focuses on the extraction of an accurate small-signal equivalent circuit for metal-oxide-semiconductor field-effect transistors (MOSFETs). An analytical modeling approach was developed and successfully validated through the comparison between measured and simulated scattering parameters. The extraction of the equivalent circuit elements allowed for the estimation of the intrinsic unity current-gain cutoff frequency, which is a crucial figure of merit for assessing the high-frequency performance. The experimental data show that the cutoff frequency of the tested devices exhibits a nearly ideal scaling behavior with decreasing gate length

A New Dynamic-Bias Measurement Setup for Nonlinear Transistor Model Identification

In this paper, we present a new dynamic-bias measurement setup and its application to the extraction of a nonlinear model for microwave field-effect transistors. The dynamic-bias technique has been recently proposed and relies on the use of low-frequency (LF) and high-frequency (HF) vector-calibrated measurements acquired, for instance, by means of a large-signal network analyzer. In this paper, we propose a new and alternative technique to perform the dynamic-bias measurements, based on relatively low-cost instrumentation commonly available in microwave laboratories. The new acquisition system is composed of a four-channel vector LF receiver (e.g., an oscilloscope) and a one-channel HF scalar receiver (e.g., a spectrum analyzer), which replace the eight-channel vector receiver. Moreover, the proposed architecture greatly simplifies the measurement setup and the calibration procedure. As a case study, a 0.25-μm GaN HEMT is considered. Dynamic-bias measurements, carried out by means of the proposed measurement setup, are used for the identification of a nonlinear model of this device. Finally, the model is fully validated through comparison with time-domain harmonic load–pull measurements carried out at 5 GHz

Evaluation of Uncertainty in Temporal Waveforms of Microwave Transistors

We evaluate the uncertainty in on-wafer vector-calibrated nonlinear measurements with the National Institute of Standards and Technology (NIST) Microwave Uncertainty Framework. We include in our analysis uncertainties in the passive calibration standards, power meter, NIST-traceable phase calibration reference, cable bending, and probe alignment. These uncertainties are propagated first to the electrical quantities across the terminals of the device-under-test, which was an on-wafer microwave transistor. Next, we propagate uncertainties to the transistor current-generator plane, whose temporal voltage/current waveforms and impedances are of interest for the design of power amplifiers

Technology-Independent Analysis of the Double Current-Gain Peak in Millimeter-Wave FETs

This letter is aimed at discovering and analyzing anomalous phenomena affecting millimeter-wave FETs, focusing on a GaN HEMT as a case study. For the first time, we show that the real parts of the impedance parameters can increase and then decrease with frequency, due to the resonance of the extrinsic reactive elements. This resonance may be detected as a peak in the magnitude of the short-circuit current-gain. Such a peak is found to be substantially bias and temperature insensitive and to manifest at frequencies higher than the other current-gain peak (CGP), due to the resonance between intrinsic capacitances and extrinsic inductances, giving origin to the double CGP

Experiment design for quick statistical FET large signal model extraction

Process variations influence the accuracy of designs and yield in production. This paper addresses the implementation of these variations in large signal FET models, with particular attention on the organization of measurements as to speed up the direct extraction of the model parameters. © 2013 IEEE

GaN HEMT model extraction based on dynamic-bias measurements

In this paper a recently proposed identification procedure based on exciting the device under test simultaneously with low-frequency (LF) large-signal excitations and a high-frequency tickle tone, is applied for the first time to GaN transistors. It will be demonstrated that the proposed technique allows reaching good prediction capability even when challenging GaN technologies are considered where LF dispersion strongly affects the transistor behavior. A dedicated formulation for the drain-source current generator is used to correctly account for dispersive phenomena. As a case study a 0.25-μm GaN HEMT is considered. The extracted model has been validated through comparison with vector nonlinear measurements carried out at 10 GHz

A Three-Port Nonlinear Dynamic Behavioral Model for Supply-Modulated RF PAs

We propose a three-port nonlinear dynamic behavioral model for supply-modulated power amplifiers (PAs). The proposed model not only accounts for the radio frequency (RF) inputoutput relationship, but also for the interaction between a modulated voltage supply, the RF output power and the supply current. The model is based on a modified Volterra formulation which accounts for the dynamic deviations with respect to a quasi-static model. The frequency-domain kernels of the proposed model are directly extracted from measurements performed with a low-frequency- extended large-signal network analyzer on an RF hand-set PA. The model is validated under random multitone modulated RF input and supply. The presented technique allows for the independent control of the RF and the supply ports. As such, it allows a separate description of both the dynamic contribution of the RF modulated input and of the dynamic supply voltage. The proposed model shows an improvement with respect to a quasi-static approach in predicting the RF output, the supply current, as well as the power-added efficiency