FinFET is a multiple-gate silicon transistor structure that nowadays is attracting an extensive attention to progress further into the nanometer era by going beyond the downscaling limit of the conventional planar CMOS technology. Although the interest for this architecture has been mainly devoted to digital applications, the analysis at high frequency is crucial for targeting a successful mixed integration of analog and digital circuits. In view of that, the purpose of this review paper is to provide a clear and exhaustive understanding of the state of art, challenges, and future trends of the FinFET technology from a microwave modeling perspective. Inspired by the traditional modeling techniques for conventional MOSFETs, different strategies have been proposed over the last years to model the FinFET behavior at high frequencies. With the aim to support the development of this technology, a comparative study of the achieved results is carried out to gain both a useful feedback to investigate the microwave FinFET performance as well as a valuable modeling know-how. To accomplish a comprehensive review, all aspects of microwave modeling going from linear (also noise) to non-linear high-frequency models are addressed.

A comprehensive review on microwave FinFET modeling for progressing beyond the state of art

A method for the complete characterization of microwave transistors in terms of noise, gain and scattering parameters using only a computer-controlled noise figure measuring set-up is presented. The selection of the optimum measuring conditions, all steps of the experimental procedure, the data collection and the processing needed to derive all the parameters are completely controlled by original (unpublished) software and do not require the presence of an (unskilled) operator. This is novel with respect to other approaches to the same problem. Experimental results regarding the characterization of 32 samples of HEMT's from four manufacturers in the 8-12 GHz frequency range are reported. >

The determination of the noise, gain and scattering parameters of microwave transistors (HEMT's) using only automatic noise figure test-set

A new approach, using electromagnetic analysis, is proposed for field-effect transistor model scaling and monolithic-microwave integrated-circuit (MMIC) design. It is based on an empirical distributed modeling technique where the active device is described in terms of an external passive structure connected to a suitable number of internal active sections. On this basis, an equivalent admittance matrix per gate unit width is obtained which, as confirmed by experimental results provided in this paper, is consistent with simple scaling rules. The same technique can also be adopted for a "global approach" to MMIC design where complex electromagnetic phenomena are also taken into account. An example of application concerning this aspect is presented.

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A new approach to FET model scaling and MMIC design based on electromagnetic analysis

In this paper, an accurate modeling procedure for GaAs MESFET as active coupled transmission line is presented. This model can consider the effect of wave propagation along the device electrodes. In this modeling technique the active multiconductor transmission line (AMTL) equations are obtained, which satisfy the TEM wave propagation along the GaAs MESFET electrodes. This modeling procedure is applied to a GaAs MESFETs by solving the AMTL equations using Finite-Difference Time-Domain (FDTD) technique. The scattering parameters are computed from time domain results over a frequency range of 20-220 GHz. This model investigates the effect of wave propagation along the transistor more accurate than the slice model, especially at high frequencies.

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Time domain analysis of active transmission line using fdtd technique (application to microwave/mm-wave transistors)

This paper compares the performance of source-tuner noise-parameter extraction methods used to measure noise parameters of low-noise amplifiers that have very low (1 dB) noise figures. The methods discussed are known as the Cold method and the modified Y -factor method (or Hot-Cold method). The paper describes equations used in the extraction algorithms. In a Monte Carlo analysis by randomly adding various sources of uncertainties to ?measurements,? created with a computer simulation, performances of the noise parameter extraction methods are compared. It is shown that the iterative Cold method and the direct Cold method are the best at extracting Rn and ?opt noise parameters in terms of lowest standard deviation and close proximity of the extracted mean values to the true values. The simplified Cold method, used in a number of commercial systems, has largest systematic offsets in extracted noise parameters while being the quickest to perform. The modified Y-factor method is the slowest to perform due to additional time required for hot measurements. This method is marginally the most accurate to extract F min. These conclusions are also supported with measurement results. This study assembles in one place necessary theoretical background information to serve as a reference for those who are working in the field of noise parameter extraction using tuner-based methods.

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Evaluation of Tuner-Based Noise-Parameter Extraction Methods for Very Low Noise Amplifiers

Simple vector concepts can be used in the determination of noise parameters from measured data. The use of such concepts leads to a simplification in the least-square fitting algorithm, complete determination of the admittance loci that produce ill conditioning, and simple criteria for the selection of source admittances that minimize the sensitivity of the noise parameters to experimental error. The sensitivity of the noise parameters to small perturbations in the reflection coefficients is compared for a group of source admittances presented in previous work. The results show that a great reduction in the error of the noise parameters can be achieved by properly selecting the source admittances. >

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A vector approach for noise parameter fitting and selection of source admittances

An appropriate scaling procedure is described for large four-finger MESFET cells with experimental verification. A comparison is presented between lumped and distributed modeling approaches. The scalability of elements in the equivalent circuit model of a MESFET is discussed. >

Distributed scaling approach of MESFETs and its comparison with the lumped-element approach

An MMIC transmitter for high-volume smart munition applications in Ka band is developed using 0.25 mu m MESFET technology. The transmitter, consisting of a voltage-controlled oscillator (VCO) and power amplifier (PA), delivers more than 100 mW of power with an overall efficiency of 10% and a linear tuning range of more than 700 MHz around 35 GHz. >

MESFET MMIC Ka-band transmitter performance for high-volume system applications

A single-ended three-stage MESFET power amplifier designed for high-volume, low-cost applications shows an average of 15-21% power added efficiency in Ka-band with 100-150 mW of power output over 30-35 GHz. Delta >

Ka-band high efficiency power amplifier MMIC with 0.30 mu m MESFET for high volume applications

A monolithic transmitter consisting of a voltage controlled oscillator and power amplifier has been successfully demonstrated for Ka-band high volume system applications (smart munitions) using nominally quarter micron MESFET technology. The results show that this technology is able to deliver good performance without compromising on yield and cost in Ka-band. With improvement in 1/f noise in HEMTs (high electron mobility transistors), it will be a viable candidate for VCOs in the future. Also shown is a unified design approach for VCOs and power amplifiers using small signal analysis. >

J.P. Mondal

Papers

A vector approach for noise parameter fitting and selection of source admittances

Distributed scaling approach of MESFETs and its comparison with the lumped-element approach

MESFET MMIC Ka-band transmitter performance for high-volume system applications

Ka-band high efficiency power amplifier MMIC with 0.30 mu m MESFET for high volume applications

MESFET MMIC Ka-band transmitter performance for high volume system applications