A new method for determining the FET small-signal equivalent circuit
01 Jul 1988-IEEE Transactions on Microwave Theory and Techniques (IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES)-Vol. 36, Iss: 7, pp 1151-1159
TL;DR: In this article, a method to determine the small-signal equivalent circuit of FETs is proposed, which consists of a direct determination of both the extrinsic and intrinsic small signal parameters in a low-frequency band.
Abstract: A method to determine the small-signal equivalent circuit of FETs is proposed This method consists of a direct determination of both the extrinsic and intrinsic small-signal parameters in a low-frequency band This method is fast and accurate, and the determined equivalent circuit fits the S-parameters well up to 265 GHz >
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TL;DR: In this paper, a method to determine the broadband small-signal equivalent circuit of field effect transistors (FETs) is proposed based on an analytic solution of the equations for the Y parameters of the intrinsic device and allows direct determination of the circuit elements at any specific frequency or averaged over a frequency range.
Abstract: A method to determine the broadband small-signal equivalent circuit of field-effect transistors (FETs) is proposed. This method is based on an analytic solution of the equations for the Y parameters of the intrinsic device and allows direct determination of the circuit elements at any specific frequency or averaged over a frequency range. The validity of the equivalent circuit can be verified by showing the frequency independence of each element. The method can be used for the whole range of measurement frequencies and can be applied to devices exhibiting severe low-frequency effects. >
357 citations
TL;DR: In this article, a decananometer-gate pseudomorphic In/sub 0.52/Al/Sub 0.48/As/In/sub0.7/Ga/sub 1.3/As high-electron mobility transistors (HEMTs) with a very short gate-channel distance was presented.
Abstract: We fabricated decananometer-gate pseudomorphic In/sub 0.52/Al/sub 0.48/As/In/sub 0.7/Ga/sub 0.3/As high-electron mobility transistors (HEMTs) with a very short gate-channel distance. We obtained a cutoff frequency f/sub T/ of 562 GHz for a 25-nm-gate HEMT. This f/sub T/ is the highest value ever reported for any transistor. The ultrahigh f/sub T/ of our HEMT can be explained by an enhanced electron velocity under the gate, which was a result of reducing the gate-channel distance.
268 citations
Cites methods from "A new method for determining the FE..."
...the measured S-parameters by using the same method as in our previous work [7] and the equivalent circuit model [12]....
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07 Nov 2005
TL;DR: In this article, a new method for extracting the parasitic elements of the GaN device is developed based on two steps, which are: 1) using cold S-parameter measurements, high-quality starting values for the extrinsic parameters that would place the extraction close to the global minimum of the objective function for the distributed equivalent circuit model are generated and 2) the optimal model parameter values are searched through optimization using the starting values already obtained.
Abstract: A new small-signal modeling approach applied to GaN-based devices is presented. In this approach, a new method for extracting the parasitic elements of the GaN device is developed. This method is based on two steps, which are: 1) using cold S-parameter measurements, high-quality starting values for the extrinsic parameters that would place the extraction close to the global minimum of the objective function for the distributed equivalent circuit model are generated and 2) the optimal model parameter values are searched through optimization using the starting values already obtained. The bias-dependent intrinsic parameter extraction procedure is improved for optimal extraction. The validity of the developed modeling approach and the proposed small-signal model is verified by comparing the simulated wide-band small-signal S-parameter, over a wide bias range, with measured data of a 0.5-/spl mu/m GaN high electron-mobility transistor with a 2/spl times/50 /spl mu/m gatewidth.
268 citations
Cites methods from "A new method for determining the FE..."
...Accurate determination for the intrinsic bias-dependent circuit of GaN HEMT SSM requires an efficient extraction method for the parasitic elements of the device....
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TL;DR: A new methodology for designing and implementing high-efficiency broadband Class-E power amplifiers (PAs) using high-order low-pass filter-prototype is proposed, which provides optimized fundamental and harmonic impedances within an octave bandwidth (L-band).
Abstract: A new methodology for designing and implementing high-efficiency broadband Class-E power amplifiers (PAs) using high-order low-pass filter-prototype is proposed in this paper. A GaN transistor is used in this work, which is carefully modeled and characterized to prescribe the optimal output impedance for the broadband Class-E operation. A sixth-order low-pass filter-matching network is designed and implemented for the output matching, which provides optimized fundamental and harmonic impedances within an octave bandwidth (L-band). Simulation and experimental results show that an optimal Class-E PA is realized from 1.2 to 2 GHz (50%) with a measured efficiency of 80%-89%, which is the highest reported today for such a bandwidth. An overall PA bandwidth of 0.9-2.2 GHz (84%) is measured with 10-20-W output power, 10-13-dB gain, and 63%-89% efficiency throughout the band. Furthermore, the Class-E PA is characterized through measurements using constant-envelop global system for mobile communications signals, indicating a favorable adjacent channel power ratio from -40 to -50 dBc within the entire bandwidth.
242 citations
Cites background or methods from "A new method for determining the FE..."
..., , , , , , and , are estimated using the method presented in [19]....
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...Typical GaN transistor model showing the parasitics [18], [19]....
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...3 shows a typical equivalent circuit of a 25-W Cree GaN HEMT (CGH40025) [18], [19], which is sealed in the Cree 440166 package....
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TL;DR: In this paper, it was shown that the high values of C/sub gd/ and G/sub ds/ combine with the high g/sub m/ to make terms involving the source and drain resistance significant.
Abstract: The usual approximate expression for measured f/sub T/=(g/sub m//2 pi (C/sub gs/+C/sub gd/)) is inadequate. At low drain voltages just beyond the knee of the DC I-V curves, where intrinsic f/sub t/ is a maximum for millimeter-wave MODFETs, the high values of C/sub gd/ and G/sub ds/ combine with the high g/sub m/ to make terms involving the source and drain resistance significant. It is shown that these resistances can degrade the measured f/sub T/ of a 0.30- mu m GaAs-AlGaAs MODFET from an intrinsic maximum f/sub T/ value of 73 GHz to a measured maximum value of 59 GHz. The correct extraction of maximum f/sub T/ is essential for determining electron velocity and optimizing low-noise performance. >
213 citations
References
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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.
258 citations
TL;DR: In this article, a method is described for accurately predicting the nonlinear microwave performance of GaAs MESFET devices using time-domain analysis and the experimentally characterized bias dependence of device-circuit model elements.
Abstract: A method is described for accurately predicting the nonlinear microwave performance of GaAs MESFET devices. The method utilizes time-domain analysis and is based upon the experimentally characterized bias dependence of device-circuit model elements. Precise predictions are made of fundamental and harmonic power levels up to 6 dB of gain compression.
123 citations
TL;DR: In this article, a procedure for producing accurate and unique small-signal equivalent circuit models for carrier-mounted GaAs FET's is presented, which utilizes zero drain-source bias S parmeter tests to determine accurate values of carrier parasitics, and dc measurements to evaluate the FETs gate, source, and drain resistances.
Abstract: A procedure has been developed for producing accurate and unique small-signal equivalent circuit models for carrier-mounted GaAs FET's. The procedure utilizes zero drain-source bias S parmeter tests to determine accurate values of carrier parasitics, and dc measurements to evaluate the FET's gate, source, and drain resistances. Subsequent S-parameter measurements at full bias are then used to resolve the FET into an equivalent circuit model that has only 8 unknown elements out of a possible 16. A technique for evaluating the frequency range of accurate data is presented and the FET model shown is useful well above the maximum frequency of measurement. Examples of device diagnostics are presented for RCA flip-chip mounted GaAs FET's.
109 citations
TL;DR: In this paper, the model previously proposed by Turner and Wilson is developed in detail and compared with experiment, and a y-parameter analysis is presented that permits calculation of transconductance and the unity current gain frequency f T.
Abstract: The model previously proposed by Turner and Wilson is developed in detail and compared with experiment. Deviations from Shockley's classical theory can be accounted for in terms of a single quantity Γ, which is related to E m the peak field for GaAs. A discussion of the physical mechanism of current saturtation shows that the formation of domains within the channel is hampered in a conventional GaAs FET. A y -parameter analysis is presented that permits calculation of transconductance and the unity current gain frequency f T . Measurements of drain current, transconductance, and f T versus gate voltage all show good agreement with values predicted by the theory. Estimates are given which show that the current saturation mechanism described will be important in the design of GaAs microwave FET's.
96 citations
TL;DR: In this paper, a simplified design-oriented equivalent circuit for the GaAs m.e.t.s. is presented, and its relation to a common, but more complex, model is derived and characteristics are compared.
Abstract: A simplified design-oriented equivalent circuit for the GaAs m.e.s.f.e.t. is presented. Its relation to a common, but more complex, model is derived and characteristics are compared. Element values are easily determined from measurements, and the simple model shows good agreement with measured parameters to 10 GHz for 1 μm-gate m.e.s.f.e.t.s.
84 citations