| 1. |
- Alderman, Byron, et al.
(författare)
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A New Pillar Geometry for Heterostructure Barrier Varactor Diodes
- 2001
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Ingår i: 12th International Symposium on Space Terahertz Technology. ; , s. 330-339
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Konferensbidrag (refereegranskat)abstract
- We report on a novel diode geometry, with reduced thermal resistance, for Heterostructure Barrier Varactor, HBV, diodes. The pillar geometry presented here involves the complete removal of the substrate, electrical contacted is made by the forward and reverse side processing of metallic pillars. We propose that there is a limit to the maximum number of barriers that can be used to increase the power capability of a HBV. An analytical model has been developed to study these effects. In considering the case of a perfect thermal heat sink the limit is found to be fourteen, in applying this model to the new pillar structure this is reduced to six.
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| 2. |
- Dillner, Lars, 1968, et al.
(författare)
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Analysis of Symmetric Varactor Frequency Multipliers
- 1997
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Ingår i: Microwave and Optical Technology Letters. ; 15:1, s. 26-29
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Tidskriftsartikel (refereegranskat)abstract
- We investigate efficiency limitations of frequency multipliers with the use of a simple model for symmetric varactors. Our calculations show that the conversion efficiency is improved for a C(V) shape with large nonlinearity at zero volt bias. For quintuplers, the optimal embedding impedance at the third harmonic is an inductance in resonance with the varactor diode capacitance.
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| 3. |
- Dillner, Lars, 1968, et al.
(författare)
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Frequency Multiplier Measurements on Heterostructure Barrier Varactors on a Copper Substrate
- 2000
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 21:5, s. 206-208
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Tidskriftsartikel (refereegranskat)abstract
- We have fabricated heterostructure barrier varactors (HBV) on a copper substrate, which offers reduced spreading resistance, and improved thermal conductivity compared to an InP substrate. The devices are fabricated without degrading the electrical characteristics. The three-barrier HBV material grown by MOVPE has a leakage current of only 0.1 mu A/ mu m/sup 2/ at 19 V. The maximum capacitance is 0.54 fF/ mu m/sup 2/. In a frequency tripler experiment a maximum output power of 7.1 mW was generated at 221 GHz with a flange-to-flange efficiency of 7.9%.
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| 4. |
- Dillner, Lars, 1968, et al.
(författare)
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Heterostructure Barrier Varactor Multipliers
- 2000
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Ingår i: GAAS 2000. - 0862132223 ; 1, s. 197-200
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Konferensbidrag (refereegranskat)abstract
- The Heterostructure Barrier Varactor (HBV) diode and its application in frequency multipliers is reviewed. Different material systems and HBV models are described. Multiplier performance versus diode parameters and some practical multiplier designs are discussed as well. The best result until now is an efficiency of 12% and an output power of 9 mW at an output frequency of 250 GHz.
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| 5. |
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| 6. |
- Dillner, Lars, 1968
(författare)
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Heterostructure Barrier Varactors for High Efficiency Frequency Multipliers
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the Heterostructure Barrier Varactor (HBV) and its application in frequency multipliers. Different HBV materials, fabrication processes, and device models are presented. The aim of this work is to improve the efficiency of HBV frequency multipliers. Efficiency limitations of symmetric varactor frequency multipliers are investigated. Simple varactor models with capacitance-voltage characteristics of varying shapes have been analyzed. Calculations show that the conversion efficiency is improved for a C(V)-shape with large non-linearity at zero-volt bias. For quintuplers, the optimal embedding impedance at the third harmonic is an inductance in reso-nance with the varactor capacitance. Results are presented from frequency tripler measurements with planar GaAs/AlGaAs HBVs. Simulations and cooled measurements show that self-heating yields excessive conduction current that decreases the efficiency. A new design of planar HBVs has been tested with improved thermal conductance and reduced series resistance. A maximum output power of 4 mW was generated at 246 GHz with an efficiency of 4.8%. A new fabrication process is presented in which HBVs are fabricated on a copper substrate. This process offers reduced parasitic losses and improved thermal conductivity and is carried out without degrading the electrical characteristics. In a frequency tripler experiment, a maximum output power of 7.1 mW was generated at 221 GHz with a flange-to-flange efficiency of 7.9%. A quasi-optical HBV tripler is presented. 11.5 mW was generated at 141 GHz with a maximum efficiency of 8%. A non-linear transmission line frequency tripler, consisting of a finline loaded with 15 HBVs, is presented. A maximum output power of 10 mW was generated at 130.5 GHz with an efficiency of 7%, and the 3 dB bandwidth was measured to 10%. A simple design method for the calculation of optimum embedding impedances, maximum efficiency, and pump power for HBV triplers is presented.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Dillner, Lars, 1968, et al.
(författare)
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High Efficiency HBV Multipliers for Millimetre Wave Generation
- 2000
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Ingår i: the XIII International Conference on Microwaves, Radar and Wireless Communications. - 8390666235 ; 3, s. 47-54
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Konferensbidrag (refereegranskat)abstract
- We describe the heterostructure barrier varactor (HBV) diode and its application in frequency multipliers. Different material systems and HBV models are described. In a frequency tripler experiment a maximum output power of 7.1 mW was generated at 221 GHz with a flange-to-flange efficiency of 7.9%.
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