HKII TEMPERATURE MICROWAVE MODELLING A N D CIRCUIT DESIGN WITH MESF:ET's A N D HBT's

V. Krozer, M. SchuBler, K. Fricke, W.-Y. Lee, N. Stolte, M. Eh-and and Hans L. Hartnagel Institut fur Hochfrequenztechnik

Technische Hochschule Darmstadt Merckstr. 25

D-64283 D,arms t ad t , Germany Phone: 4-49 6151 162162

email:

ABSTRACT

Nove l mzcrowave circui t s truct irres have signed and fabricated /or appl icat ion a t h igh

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been de- operat ing

t e in pe ra t ii res. T h e required s i m U. 1 a t i o n a n d c Ii a ra c t e r- t za t ion of MESFET and HBT devices a t h igh a m b i e n t t empera tures have been carried out. N o v e l phys i ca l an.- alylical mode l s for t h e high t empera ture p e r f o r m a n c e of MESFET's and H B T s were developed. A s a n e z - a m p l e a f u l l y integrated radar f r o n t - e n d operat ing a t t empera tures u p to 200°C is g iven in t h e paper.

1 INTRODUCTION

MMIC design and fabrication for high tempera- ture applications have recently received increased at- tention. Most MMIC for high temperature applica- tions considered up to date have been realized with MESFET or HEMT technologies. Also I-IBT devices have been proposed for high temperature applications

The design of MMIC for high temperatures requires accurate modeling and characterization of devices a t increased operating ambient temperatures. A number of physical and empirical models for MESFET devices have been presented in the literature. RBT device modeling has not yet reached this maturity and new resiilts will be presented in this paper.

'The scope of this contribution is to demonstrate novel MMIC designs intended for high temperature application and new results for the characterization of HBT devices for a temperature range up to 25OoC.

[I, 2, 3, 4, 51.

It is commonly accepted and has been confirmed by us earlier [l] that only Szl of MESFET devices de-. creases by approximately a factor of 2 with increasing temperature from room temperature to 20OoC. As the other scattering parameters remain unchanged up to 0-7803-2516-8195 $4.00 0 1995 IEEE 343

P 1

U

I - -20 25 50 75 100 125 15CI 175

5 1 -

Temp. I 'c

Figure 1: High temperature VCO and measured re- sults for the frequency of oscillation arid the output power as a function of ambient temperature.

rensoning a M[MI:C VCO has been designed and re- alized. In fig. 1 the design and the measured per- formance are illustrated. N o special measures have been undertaken in this circuit to stabilize the output power versus temperature and therefore the output

I

Figure 2: Active circulator with integrated mixer

power drops at temperatures above 15OoC. A second circuit has been designed which comprises

an active circulator with a mixer circuit designed to operate up to 2OO0C ambient temperature. The cir- cuit is shown in fig. 2. The circulator utilizes a

common-source configuration as an out-of-phase di- vider and a common gate pair as a mixer. T h e circu- lator does not exhibit a return path and could there- fore also be called a diplexer because of its ability to deliver the signal from the input to the antenna port and from the antenna port to the mixer. T h e simu- lated performance of the circulator is summarized in fig. 3a and fig. 3b where the scattering parameters and the output IF current are indicated.

3 MODELLING AND CHARACTERIZATION

OF H B T FOR HIGH TEMPERATURES

HBT devices offer a number of advantages with respect to high temperature applications when com- pared with MESFET devices. Most notably the verti- cal current flow and the possibility of heterostructur- ing yield higher flexibility in the design of HBT devices and circuits. Little is known on the high temperature microwave performance of HBT devices and there are no HBT device models available capable of accurately characterizing the H B T high temperature behavior. We have developed a DC and RF HBT model appli- cable for the simulation of the operation a t increased temperatures [a, 3, 4, 5 , 6, 71. A comparison between measured and calculated DC characteristics at room temperature and at 2OO0C are given fig. 4. Very good

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Figure 3: Simulated results for the a) scattering pa- rameters and b) for the I F current at the output port of the circulator with integrated mixer.

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Acknowledgments

-simulated T = 300K measured

base step = 200pA

30

' I 0 1 2 3 4 5 6

Vce ( V )

a

b

Figure 4: Measured and Calculated I/V characteris- tics at a) room temperature and b) 200°6.

agreement between measured and calculated results can be achieved with this physical model. It will be demonstrated during the presentation that the R.F performance of HBT resembles the high temperature operating conditions of MESFETs. For example the main deterioration in device performance is observed for the simulated as well as measured &I.

4 CONCLUSIONS

We have demonstrated MMIC circuits based on MESFET devices operating at high ambient temper- atures. It has also been shown tha t HBT devices ex- hibit a similar high temperature performance as the MESFET. A new model developed for the simulation of HBT devices greatly facilitates the temperature de- pendent design of MMIC based on HBT.

This worlk was supported in part by the I3undesmin- isterium fiiir Flxschung und Technologie (ISMFT), by the Deutsche I'orschungsgemeinschaft (DFG) . The au- thors are grateful to Dr. J . Wiirfl, Ferdinand-Braun- Institut fur Htjchstfequenztechnik, Berlin for supply- ing DC da ta for the high temperature MIESFET de- vices and for the fabrication of the MESFET circuits.

References

[l] K. Fricke, W.Y. Lee, V. Krozer, J. Wiirfl, S. Bialas, and H.L. Hartnagel: Microwave Characteriza- tion ' and Comparison of Performance of GaAs based MESFETs, HEMTs and HBTs Operating a t High Ambilsnt Temperatures, GAAS'92, European Gallium A,rsenide and Related 111- V Compounds Application Symp., Noordwijk, The Netherlands, April 27-29, 1992.

[2] W.-Y. Lee, K. Fricke, V. Krozer, M. SchiiBier, and H.L. Hartnagel: AlGuAslGaAs HBT for Microwave Applications up to 24OoC, Workshop on High-speed Bipolar Circuits and Detvices, Ulm, Germany, Oct. 11-12, 1993.

[3] K. Fricke, V. Krozer, W.U. Lee, M. Ruppert, M. SchiiBler, G. Schweeger, A. Sigurdardottir , and H.L. Hartnagel: Design and Technology of AlGuAs,lGtzAs HBT for High Temperature Cir- cuits, GAAS'94, European Gallaum Arsenade and Related 111- V Compounds Applicatr!on Symp., Torino, Italy, April 28-30, 1994.

[4] V. Krozer, M. Ruppert, W.Y. Lee, J. Gra- jal , A. Goldhorn, M. SchiiBler, K. Fricke, and H . L . Hal: t ni2gel: A Physics- Based Temper a t ure- Dependent SPICE Model for the Simulation of High Temperature Microwave Performance of HBT's a.nd Experimental Results, 1994 IEEE MTT-S, Ini!ern. Microwave Symp. Dig., Mai 23- 27,1994.

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[ 5 ] V . Krozer, M. Ruppert, J.-M. Miao, W.Y. Lee, M . SchuBler, K . Fricke, and H.L. Hartnagel: Mod- elling of High Temperature Performance of MES- FET’s and HBT’s, HITEC’94, High Temperature Electronics Symposium, Mai 23-27,1994.

[6] M. SchuBler, K. Fricke, W.-Y. Lee, V. Krozer, and H.L. Hartnagel: Collector Design for Improved Breakdown in High Temperature AlGaAslGaAs HBT, EDMO’93, Workshop on High Perfor- mance Electron Devices for Microwave and Opto- electronic Applications, London, England, Oct. 18, 1993.

[7] V . Krozer, M. Ruppert, M. SchuBler, K . Fricke, W . Y . Lee, and H.L. Hartnagel: Calculation of the Power Capabilities of HBT Amplifiers Based on a New Physical HBT Model, INMMC’94, IEEE MTT/AP 3rd Intern. Workshop on Inte- grated Ninlinear Microwave and Millimeterwave Circuits, Duisburg, Germany, 5th-7th Oct. 1994.

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