Propagation effects on Z Parameters in an FET equivalent circuit

M. Balti,
ENIT, Tunis, Tunisia

D. Pasquet,
ENSEA/ECIME, Cergy, France,
pasquet@ensea.fr

M. Ariaudo,
ENSEA/ECIME, Cergy, France

A. Samet,
EPT, La Marsa, Tunisia

DOI: 10.36724/2664-066X-2021-7-5-21-25

SYNCHROINFO JOURNAL. Volume 7, Number 5 (2021). P. 21-25.

Abstract

The design of microwave circuits needs a good analysis of the performances of the field-effect transistor equivalent circuit. Indeed the small signal equivalent circuit of the field-effect transistors makes it possible to easily determine their performances such as the gain and the noise figure. A field-effect transistor constitutes a propagation structure along its gate width. Telegraphists’ equations are solved for this structure. One deduces from this the effect of the propagation on the transistor Z-parameters which can be taken into account in electric simulations and which may improve the use of long transistors at lower frequencies and of short transistors at higher frequencies.

Keywords: FET equivalent circuit, field-effect transistor, microwave circuits, Z-parameters

References

[1] C. Byl, Y. Crosnier. Modeling and optimisation of travelling wave field effect transistors, Journ. Of Electromagnetic Waves Applications, (1991), pp. 419-438.
[2] R.L. Chang, T.J. Shieh, W.A. Davis, R.L. Carter. Modeling and analysis of GaAs MESFETs considering the wave propagation effect, IEEE MTT-Symposium Digest 1989, pp. 371-374.
[3] W. Heinrich. Limits of FET modelling by lumped elements, Electronics Letters, Vol 22 (1986), pp. 630-632.
[4] W. Heinrich, H.L. Hartnagel. Wave propagation on MESFET electrodes and its influence on transistor gain, IEEE Trans. on MTT, Vol. MTT-35 (1987), pp. 1-8.
[5] M. Ariaudo, E. Bourdel, D. Pasquet. Variation in intrinsic parameters of transistor with gate width, Electronics Letters, Vol. 36, n° 15 (juillet 2000), pp. 1323-1325.
[6] A.J. Holden, D.R. Daniel, L. Davies, C.H. Oxley, H. Rees. Gallium arsenide travelling field effect transistors, IEEE. Trans. Electrn. Devices, Vol. 32, No. 1, Jan. 1985.
[7] Y.A. Ren, H.L. Hartnagel. Traveling wave power FET with coplanar slow-wave electrode system modelling and experimental results, AEU repot., 36, pp. 468-474, 1982.
[8] W. Heirich. Distributed equivalent-circuit model for travelling wave FET design, IEEE. Trans. Microwave theory Tech., Vol. MTT-35, No. 5, May 1987.
[9] W. Heirich, H.L. Hartnagel. Field-theoretic analysis of wave propagation on FET electrodes includind losses and small signal amplification, Int. J. Electron., Vol. 58, pp. 613-627, 1985.