Microwave properties of Schottky-barrier field-effect transistors
IBM1
TL;DR: In this paper, the microwave properties of the Schottky-barrier field effect transistor (MESFET) with a gate-length of one micrometer are investigated.
Abstract: The microwave properties of silicon Schottky-barrier field-effect transistor(MESFET'S) with a gate-length of one micrometer are investigated. The scattering parameters of the transistors have been measured from 0.1 GHz up to 12 GHz. From the measured data an equivalent circuit is established which consist of an intrinsic transistor and extrinsic elements. Some of the elements of the intrinsic transistor, notably the transconductance, are strongly influenced by the saturation of the drift velocity. Best performance of the intrinsic transistor is obtained with highly doped and thin channels. The measured power-gain is in good agreement with theoretical values deduced from the equivalent circuit. The best device has a maximum frequency of oscillation fmax of 12 GHz. The investigation reveals that the extrinsic elements, especially the resistance of the gate-metallization and the gate-pad parasitics, degrade the power-gain considerably. Without them a value of fmax close to 20 GHz is predicted.
Citations
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TL;DR: In this article, the authors examined the signal and noise properties of gallium arsenide (GaAs) microwave field effect transistors (FETs) and found that radiofrequency instabilities due to this region, if they exist, occur at frequencies far above the normal frequency regime of microwave FETs.
Abstract: Publisher Summary This chapter examines the signal and noise properties of gallium arsenide (GaAs) microwave field-effect transistors (FET) High frequency gallium arsenide field-effect transistors (GaAs FETs) have demonstrated remarkably low noise figures and high power gains at microwave frequencies A practical microwave GaAs FET is usually fabricated by deposition or diffusion of source, gate, and drain contacts on the surface of an appropriately doped thin epitaxial n-type layer This layer, in turn, is grown on a semi-insulating wafer by either a vapor or liquid epitaxial technique The apparent minor role played by the negative resistance region in practical short-gate FETs suggests that radiofrequency instabilities due to this region, if they exist, occur at frequencies far above the normal frequency regime of microwave FETs The small-signal equivalent circuit of the FET, valid up to moderately high frequencies is elaborated It is found that noise in a microwave GaAs FET is produced both by sources intrinsic to the device and by thermal sources associated with the parasitic resistances
471Â citations
24 May 2013
TL;DR: The properties of graphene relevant for electronic applications are discussed, its advantages and problems are examined, and the state of the art of graphene transistors are summarized.
Abstract: Graphene is a relatively new material with unique properties that holds promise for electronic applications. Since 2004, when the first graphene samples were intentionally fabricated, the worldwide research activities on graphene have literally exploded. Apart from physicists, also device engineers became interested in the new material and soon the prospects of graphene in electronics have been considered. For the most part, the early discussions on the potential of graphene had a prevailing positive mood, mainly based on the high carrier mobilities observed in this material. This has repeatedly led to very optimistic assessments of the potential of graphene transistors and to an underestimation of their problems. In this paper, we discuss the properties of graphene relevant for electronic applications, examine its advantages and problems, and summarize the state of the art of graphene transistors.
445Â citations
Cites background from "Microwave properties of Schottky-ba..."
...and useful approximations for the corresponding extrinsic frequencies of the whole FET are [35], [37], [38]...
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TL;DR: In this article, the analysis of GaAs MESFET distributed amplifiers and a systematic approach to their design are presented, focusing on fundamental design considerations and also establishing the maximum gain-bandwidth product of the amplifier.
Abstract: In the paper, the analysis of GaAs MESFET distributed amplifiers and a systematic approach to their design are presented. The analysis focuses on fundamental design considerations and also establishes the maximum gain-bandwidth product of the amplifier.The design approach presented enables one to examine the tradeoffs between the variables, such as the device, the number of devices, and the impedances and cutoff frequency of the lines, and arrive at a design which gives the desired frequency response. Excellent agreement is shown when the theoretically predicted response of a typical amplifier is compared with computer-aided analysis results, and good agreement is shown with previously published experimental results.
349Â citations
TL;DR: In this paper, the active channel properties of a gallium arsenide (GaAs) metal-semiconductor field effect transistor (mesfet) were determined using simple analytical expressions developed in terms of the geometrical and material parameters of a device.
Abstract: This paper describes a new technique to determine the basic properties of the active channel of a gallium arsenide (GaAs) metal-semiconductor field effect transistor (mesfet). The effective gate length, channel thickness, and carrier concentration are determined from dc parameters. A precise method of measuring the dc parameters is also given. The new techniques are demonstrated using a wide variety of sample devices. It is also shown that microwave performance parameters, such as the maximum output power and minimum noise figure, are well predicted by dc parameters. Calculated values of the intrinsic and extrinsic dc parameters, using simple analytical expressions developed in terms of the geometrical and material parameters of a device, are shown to be in excellent agreement with their measured values. These expressions can be used as a basis for device design.
258Â citations
TL;DR: In this article, the impact of gate resistance on cut-off frequency, maximum frequency of oscillation (f/sub max/), thermal noise, and time response of wide MOS devices with deep submicron channel lengths was analyzed.
Abstract: This paper describes the impact of gate resistance on cut-off frequency (f/sub T/), maximum frequency of oscillation (f/sub max/), thermal noise, and time response of wide MOS devices with deep submicron channel lengths. The value of f/sub T/ is proven to be independent of gate resistance even for distributed structures. An exact relation for f/sub max/ is derived and it is shown that, to predict f/sub max/, thermal noise, and time response, the distributed gate resistance can be divided by a factor of 3 and lumped into a single resistor in series with the gate terminal. >
230Â citations
Cites background from "Microwave properties of Schottky-ba..."
...Using various approximations, several authors have calculated fmar for MESFETs with finite gate resistance [5], [6]....
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References
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TL;DR: In this paper, the physical meaning and prop-erties of the power waves defined by [Equation], [ Equation] where V/sub i/ and Z/sub I/ are the voltage at and the current flowing into the ith port of a junction and the impedance of the circuit connected to the it h port.
Abstract: This paper discusses the physical meaning and prop-erties of the waves defined by [Equation], [Equation] where V/sub i/, and Z/sub i/, are the voltage at and the current flowing into the ith port of a junction and Z/sub i/, is the impedance of the circuit connected to the ith port. The square of the magnitude of these waves is directly related to the exchangeable power of a source and the reflected power. For this reason, in this paper, they are called the power waves. For certain applications where the power relations are of main concern, the power waves are more suitable quantities than the conventional traveling waves. The lossless and reciprocal conditions as well as the frequency characteristics of the scattering matrix are presented. Then, the formula is given for a new scattering matrix when the Z/sub i/'s are changed. As an application, the condition under which an amplifier can be matched simultaneously at both input and output ports as well as the condition for the network to be unconditionally stable are given in terms of the scattering matrix components. Also a brief comparison is made between the traveling waves and the power waves.
906Â citations
01 Nov 1952
TL;DR: In this article, the authors proposed a new form of transistor called unipolar field effect transistor, which is of the "field effect" type in which the conductivity of a layer of semiconductor is modulated by a transverse electric field.
Abstract: The theory for a new form of transistor is presented. This transistor is of the "field-effect" type in which the conductivity of a layer of semiconductor is modulated by a transverse electric field. Since the amplifying action involves currents carried pre-dominantly by one kind of carrier, the name "unipolar" is proposed to distinguish these transistors from point-contact and junction types, which are "bipolar" in this sense. Regarded as an analog for a vacuum-tube triode, the unipolar field-effect transistor may have a m? of 10 or more, high output resistance, and a frequency response higher than bipolar transistors of comparable dimensions.
645Â citations
TL;DR: In this paper, it was shown that the stability of a linear two-port is invariant under arbitrary lossless terminations, under interchange of input and output, and under "immittance substitution", a transformation group involving the arbitrary interchanging of impedance and admittance formulations at both ports.
Abstract: It is shown that the stability of a linear twoport is invariant under arbitrary lossless terminations, under interchange of input and output, and under "immittance substitution," a transformation group involving the arbitrary interchanging of impedance and admittance formulations at both ports. The quantity k = \frac {2 Re (\gamma_{11}) Re (\gamma_{22}) - Re(\gamma_{12} \gamma_{21})} {|\gamme_{12} \gamma_{21}|} (where the \gamma may be any of the conventional immittance z, y, or hybrid h, g matrix parameters) is the simplest invariant under these transformations, and describes uniquely the degree of stability, provided Re(\gamma_{11}), Re(\gamma_{22}) \geq 0; the larger k is, the greater the stability, and in particular k = 1 defines the boundary between unconditional and conditional stability. The quantity k is thus the basic invariant stability factor. Its definition is also extended to include the effect of terminating immittances, which may be padding resistances or source and load immittances, or both. Certain power-gain functions, including the maximum available power gain, are shown to be invariant under immittance substitution, and k is identified as a function of ratios between them, where they exist. This provides a fundamental way of determining k, apart from calculating it from matrix parameters, and indicates that it is a measure of an inherent physical property.
378Â citations
TL;DR: In this paper, a linear three-terminal device Z is imbedded in a lossless passive network N and the properties of the complete system, as measured at two specified terminal pairs, are described by the open-circuit impedances Z_{11, Z_{12}, Z_{21, and Z_22.
Abstract: A linear three-terminal device Z is imbedded in a lossless passive network N and the properties of the complete system, as measured at two specified terminal pairs, are described by the open-circuit impedances Z_{11}, Z_{12}, Z_{21}, and Z_22 . A search for properties of Z which are invariant under the transformation N leads to the quantity U = \frac{|Z_{21}-Z_{12}|^2}{4(R_{11}R_{22}-R_{12}R_{21})} where R_{jk} is the real part of Z_{jk} . Quantity U is independent of the choice of N and is (consequently) invariant under permutations of the three terminals and also under replacement of the open-circuit impedances by short-circuit admittances. If U exceeds unity at a specified frequency, then N can always be chosen to make R_{11} and R_{22} positive and Z_{12} zero at that frequency. Quantity U is identifiable as the available power gain of the resulting unilateral structure. An arbitrary coupling network may be decomposed into a portion which accomplishes unilateralization and a remaining complementary portion which provides feedback around the unilateralized structure. Such decomposition brings some of the notions of elementary feedback theory to bear upon nonunilateral circuit analysis and offers a viewpoint from which signal flow and power flow are simply related.
287Â citations
01 Feb 1966
TL;DR: The Schottky barrier gate as mentioned in this paper is a metal in intimate contact with the clean semiconductor surface, which can be placed either on top of or under the semiconductor layer.
Abstract: An obvious addition to the ever-growing family of field-effect devices is a field-effect transistor with a Schottky barrier gate. It is the purpose of this correspondence 1) to demonstrate that indeed such a device does function as expected and 2) to point out several advantages of such a structure under certain circumstances. A schematic cross section of the device is shown in Fig. 1. The gate consists of a metal in intimate contact with the clean semiconductor surface. Clearly the ohmic contacts can be placed either on top of or under the semiconductor layer.
125Â citations