Analytical noise model with the influence of shot noise induced bythe gate leakage current for submicrometer gate-lengthhigh-electron-mobility transistors

A new high-frequency noise model which takes into account the influence of shot noise induced by the gate leakage current is introduced; the model accurately explains the observed minimum noise figure of submicrometer gate-length HEMT's as a function of frequency. Based on the steady-state Nyquist theorem for multiterminal devices recently reported, the minimum noise figure and the corresponding optimum source impedance of the microwave field effect transistors are expressed as functions of the measurable device parameters including noise spectral intensities and small-signal circuit parameters. The derived minimum noise figure can be shown to reduce to a simple form, i.e., an empirical relation with two fitting constant. The simple form and the derived formulas for the optimum source impedance can explain very well the experimental findings of the submicrometer gate-length high electron mobility transistors over the extended microwave frequency range and also provide the informations needed for the design of microwave low noise amplifiers     

A simplified approach to optimum noise source impedance determination for GaAs FET amplifiers

A simple, analytical approach to determine the optimum noise source impedance of a GaAs FET amplifier in the 3-12 GHz frequency range is developed. The procedure can also be used in the 0-5—3 GHz range, but the model on which the procedure is based may be less accurate in this frequency range. The approach requires knowledge of the transistor's small-signal model parameters and its minimum noise temperature versus frequency. The approach is relatively insensitive to errors in the value of the GaAs FET small-signal parameters, but noise in the required minimum noise temperature data is potentially a source of nonlinear errors in the computed value of the optimum noise source impedance with respect to the error in the minimum noise temperature data The amount of error in the computed value of optimum noise source resistance is roughly proportional to the error in the minimum noise temperature data when the error at each data point is correlated, while the error in the computed value of the optimum noise source reactance is roughly three times the error present in the minimum noise temperature data. When the error is uncorrelated, the method does not yield acceptable results.     

High-frequency FET noise performance: a new approach

A formulation is proposed for calculating the FET noise performance in the high-frequency range (EHF). In the first step, the concept of a local small-signal equivalent circuit is introduced, and a novel method for calculating the FET admittance parameters is proposed. In the second step, a novel formulation of the impedance field is given. It is shown that this approach reflects better the frequency evolution of the noise source values and consequently gives a better noise figure     

Noise factor contours for field-effect transistors at moderately high frequencies

This analysis of noise behavior is based on an equivalent circuit for the junction field-effect transistor (FET) that was previously published [10]. Since all noise sources in this equivalent circuit are uncorrelated and all significant parasitic elements are already considered, one may apply an easy and direct calculation for the noise factor, which is carried out for the common source, common gate, and common drain configurations. As a result, the constant noise factor contours are represented as circles in the plane of the complex source admittance Y8. This plot of circles is valid above 1/f noise up to moderately high frequencies, and is arrived at by a frequency-dependent normalization of the axis. It is shown that the plot is fully characterized by two frequency-dependent values: the optimum source admittanceY_{8} {opt}and the minimum noise factor Fmin, both being derived from the small-signal equivalent circuit of the FET and the bias condition. The results are in agreement with the commonly held opinion that the noise factor does not differ very much for the three basic configurations [9]. Finally, the theoretical results are verified by measurements at 30 and 60 MHz.     

LOW-FREQUENCY LOW-NOISE CIRCUITS DESIGN USING AN E_n-I_n MODEL

In view of the limitations of a Rn-Gn model in the low frequency range and the defects of an En-In model in common use now, this paper builds a complete En-In model according to the theory of random harmonic. The parameters for the low-noise design such as the equivalent input noisy voltage Ens, the optimum source impedance Zsopt and the minimum noise figure Fmin can be calculated accurately by using this En-In model because it considers the coherence between the noise sources fully. Moreover, this paper points out that it will cause the maximum 30% miscalculation when neglecting the effects of the correlation coefficient 7. Using the series-series circuits as an example, this paper discusses the methods for the En-In noise analysis of electronic circuits preliminarily and demonstrates its correctness through the comparison between the simulated and measured results of the minimum noise figure Fmin of a single current series negative feedback circuit.     

Microwave Power GaAs FET Amplifiers

The development of broad-band microwave amplifiers using state-of-the-art GaAs power FET's covering the 6-12-GHz frequency band is presented. A unique circuit topology incorporating an edge-coupled transmission line section for both impedance matching and input/output dc blocking is described. The microstrip circuit design of an X-band 1-W 22-dB-gain GaAs FET amplifier is also discussed. Microwave performance characteristics such as intermodulation, AM-to-PM conversion, and noise figure are included.     

Determining intrinsic noise parameters of 0.25 mu m gate pseudomorphic HEMT

An accurate equivalent circuit of a pseudomorphic HEMT (PM-HEMT) has been used, together with physically realistic values for the intrinsic PM-HEMT noise parameters (P, R, and C) to estimate the extrinsic noise parameters (minimum noise figure, optimum noise impedance, etc.) of a 0.25 mu m gate PM-HEMT. It is demonstrated that good agreement with experiment can be obtained for the minimum noise figure, optimum noise impedance, and also noise resistance, over the frequency range 6-18 GHz.<>     

Microwave Noise Characterization of GaAs MESFET's: Evaluation by On-Wafer Low-Frequency Output Noise Current Measurement

A simplified noise equivalent circuit is presented for submicron-gate-length MESFET's in the common-source configuration, consisting of five linear circuit elements: the gate-to source capacitance C/sub gs/, the total input resistance R/sub T/, the transconductance g/sub m/, the output resistance R/sub 0/, and a noise current source of spectral density S/sub io/ at the output port. All of these elements can be determined by on-wafer measurements, and the noise current can be measured at a low frequency. The minimum noise figure of the device calculated from this model, as well as the bias and frequency dependence of the noise figure, is shown to be in agreement with microwave noise figure measurements. Thus a technique has been established for determination of the minimum noise figure of a device solely by on-wafer measurements rather than by the usual microwave measurements. The proposed technique can be employed rapidly, conveniently, without the need for tuning, and at the wafer stage of device fabrication.     

A new extraction method for noise sources and correlationcoefficient in MESFET

A new extraction method for noise sources and correlation coefficient in the noise equivalent circuit of GaAs metal semiconductor field effect transistor (MESFET) is proposed. It is based on the linear regression, which allows us to extract physically meaningful parameters from the measurement in a systematic and straightforward way. The confidence level of the measured data can also be easily examined from the linearity, y-intercept of the linear regression, and the scattering from the regression line. Furthermore, it is found that the time constant of correlation coefficient whose value is almost the same as that of the transconductance should be considered to model noise parameters accurately. The calculated values of minimum noise figure, optimum impedance, and noise resistance using above approach, show excellent agreement with measurement for a typical MESFET device studied in this paper     

Two-port noise and impedance measurements for two-terminal deviceswith a resonant tunneling diode example

A two-port technique is presented for determining the circuit elements and noise sources of the equivalent circuit of a two-terminal device at microwave frequencies. The two-terminal device is connected as a two-port so that intrinsic and parasitic circuit elements can be obtained from full two-port S-parameter measurements. This measurement does not require one of the two contacts to be grounded, which makes it particularly well suited for the characterization of integrated devices where parasitic elements become important and cannot be easily calculated. The noise of the device is measured by employing a noise-figure meter and the intrinsic noise is computed from the measured terminal noise. As an example, the impedance and noise elements of a resonant tunneling diode (RTD) are measured over frequency ranges of 2-8 and 2-4 GHz, respectively     

Improvement in the tetrode FET noise figure by neutralization and tuning

The noise figure of the tetrode FET is calculated, and it is shown that for frequencies near the cutoff frequency of the FET a considerable improvement in noise figure is possible by neutralizing the drain-gate capacitance C/SUB dg/ of the first half of the tetrode and by tuning the interstage network between the first and second half of the tetrode FET. To make this improvement possible, the tetrode FET must be provided with one extra lead connecting drain 1 + source 2 to the outside. The improvement is demonstrated for an FET cascode circuit.     

Analytical Determination of MOSFET's High-Frequency Noise Parameters From NF50 Measurements and Its Application in RFIC Design

An analytical method, along with closed-form solutions, to determine high-frequency (HF) noise parameters of the MOSFET from its noise figure (NF) measurements with an arbitrary source impedance is presented and experimentally verified. This method allows for the determination of the minimum noise figure, NF_min, equivalent noise resistance, R_n, and optimum source admittance Y_opt , of MOSFET directly from a single high-frequency 50-Omega noise figure measurement and a model characterization based on the transistor's measured scattering parameters. The proposed method can accurately predict the noise parameters of deep-submicron MOSFETs, and hence is useful in the design of low-noise radio-frequency integrated circuits (RFICs). Application of the proposed method in the design of CMOS RF low-noise amplifiers (LNAs) is also discussed     

Noise in transistor mixers

Starting from the physical sources of noise in junction transistors, an equivalent noise circuit for a high frequency mixer circuit is presented. By means of formulas which have been derived for normal amplifiers and mixers the noise current components in the collector circuit are computed. These noise current components at the intermediate frequency are due to diverse amplifying and mixing processes. The dependence of the derived noise factor upon working point, generator output resistance, frequency and oscillator voltage is verified. The noise figure exhibits a minimum not only as a function of the generator output resistance but also as a function of the collector direct current. The noise figure may be optimized by choosing appropriate values for the circuit components and the operating point. Finally, the application of the noise formula to a dc-stabilized mixer stage is presented.     

微波集成公度线FET放大器的简化实频技术设计法

将简化实频技术发展用于具有公度线匹配网络的微波集成FET多级放大器的设计。勿需FFT的数学模型,勿需设定匹配网络的拓扑,按照通带内的噪声系数与传输增益指标要求可直接求得最佳的网络散射矩阵,据此即可综合公度线匹配网络。设计的实践证明此方法是适用于工程实际的。     

On the noise performance of bipolar transistors in untuned amplifiers

From a generalized approach this paper reexamines the noise performance of bipolar transistors in untuned amplifiers. New results are obtained for the upper corner frequency which fully characterize the frequency dependent noise figure curves under conditions of arbitrary and optimum source conductance termination. The effects of the collector bias current on the minimum noise figure, the optimum source conductance and the upper noise corner frequency are presented both analytically and graphically. The results also include the effects of source capacitance on noise figures. A systematic design of low-noise untuned low-pass amplifiers with desired gain-bandwidth performance can be readily achieved with the help of the results presented.     

Modeling of distributed parasitics in power FETs

A distributed circuit analysis of power FETs accounting for the lateral source parasitic impedance in addition to the lateral drain and gate parasitic impedances is presented. Both a numerical solution and an exact analytic solution are derived. Using the exact analytic solution, approximate equivalent circuits are derived for FETs of short gate width for two common types of boundary conditions. When the gate and drain terminals are located on opposite sides of the distributed FET, the lateral source parasitic impedance can be represented for short gate width FETs by an equivalent circuit with a negative series impedance in series with the source terminal. The practical consequences on parameter extraction for device modeling are discussed. The availability of an exact analytic solution for the distributed FET should also assist with the synthesis of traveling wave FETs.     

Modeling of noise parameters of MESFETs and MODFETs and theirfrequency and temperature dependence

A simple noise model of a microwave MESFET (MODFET, HEMT, etc.) is described and verified at room and cryogenic temperatures. Closed-form expressions for the minimum noise temperature, the optimum generator impedance, the noise conductance, and the generator-impedance-minimizing noise measure are given in terms of the frequency, the elements of a FET equivalent circuit, and the equivalent temperatures of intrinsic gate resistance and drain conductance to be determined from noise measurements. These equivalent temperatures are demonstrated in the case of a Fujitsu FHR01FH MODFET to be independent of frequency in the frequency range in which 1/f noise is negligible. Thus, the model allows prediction of noise parameters for a broad frequency range from a single frequency noise parameter measurement. The relationships between this approach and other relevant studies are established     

Notes on a Crystal Mixer Performance

A simple relation between optimum rf source impedance for minimum noise figure and the nominal conversion loss of a mixer is derived. This impedance is related to the input mismatch and its dependence on the type of IF amplifier input circuit is discussed. Relations between the crystal noise temperature and mixer noise temperature as a function of conversion loss are derived for different load conditions at the image frequency terminals.     

The noise performance of microwave transistors

Expressions for the noise parameters of microwave transistors are derived. The theory is based on a small-signal common-emitter equivalent circuit which includes a new basic noise equivalent circuit and the dominanting header parasitics. The theory is verified experimentally in the L-band (1 to 2 Gc/s) frequency range using Ge and Si microwave transistors. It is found that the header parasitics have little influence on the minimum noise figure, but do have large effects on the equivalent noise resistance and the optimum source admittance in the frequency region above about one-half of the series-resonant frequency resulting from the parasitics in conjunction with wafer parameters. For a quick evaluation of the noise performance, new approximate expressions are also given for the noise figure and for the optimum current which produces the lowest value.     

Internal thermal feedback in four–poles especially in transistors

Thermal-electric interaction or "internal thermal feedback" occurs in temperature dependent devices and four-poles at low frequencies, if the thermal time constants are small. An electrical equivalent circuit which describes this thermal effect is generally derived and applied to transistors in common base and common emitter configuration. It consists of current sources and of resistance-inductance circuits which can be directly related to the thermal equivalent circuit of the device. It is shown that this thermal feedback should not be neglected in the measurement of high-frequency transistors, in the design of dc or video amplifiers and voltage or current regulators. Some measurements are reported and discussed. For instance, a strong frequency dependence of some four-pole parameters, especially of the forward trans-conductance y21and the short circuit output admittance y22eof high frequency transistors was found at frequencies below 1 Mc. These effects can be explained by the new equivalent circuit. Possible application of this thermal-electric interaction may include the realization of large low Q inductances for low frequency integrated circuitry, and perhaps the investigation of pinch-in and second breakdown effects. It appears that the low frequency noise figure of transistors may also be affected by this effect.