| 1. |
- Alderman, Byron, et al.
(author)
-
A New Pillar Geometry for Heterostructure Barrier Varactor Diodes
- 2001
-
In: 12th International Symposium on Space Terahertz Technology. ; , s. 330-339
-
Conference paper (peer-reviewed)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.
|
|
| 2. |
- Dillner, Lars, 1968, et al.
(author)
-
Analysis of Symmetric Varactor Frequency Multipliers
- 1997
-
In: Microwave and Optical Technology Letters. ; 15:1, s. 26-29
-
Journal article (peer-reviewed)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.
|
|
| 3. |
- Dillner, Lars, 1968, et al.
(author)
-
Frequency Multiplier Measurements on Heterostructure Barrier Varactors on a Copper Substrate
- 2000
-
In: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 21:5, s. 206-208
-
Journal article (peer-reviewed)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%.
|
|
| 4. |
- Dillner, Lars, 1968, et al.
(author)
-
Heterostructure Barrier Varactor Multipliers
- 2000
-
In: GAAS 2000. - 0862132223 ; 1, s. 197-200
-
Conference paper (peer-reviewed)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.
|
|
| 5. |
|
|
| 6. |
- Dillner, Lars, 1968
(author)
-
Heterostructure Barrier Varactors for High Efficiency Frequency Multipliers
- 2000
-
Doctoral thesis (other academic/artistic)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.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Dillner, Lars, 1968, et al.
(author)
-
High Efficiency HBV Multipliers for Millimetre Wave Generation
- 2000
-
In: the XIII International Conference on Microwaves, Radar and Wireless Communications. - 8390666235 ; 3, s. 47-54
-
Conference paper (peer-reviewed)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%.
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
- Fu, Ying, 1964, et al.
(author)
-
AlGaAs/GaAs and InAlAs/InGaAs Heterostructure Barrier Varactors
- 1997
-
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 82:11, s. 5568-5572
-
Journal article (peer-reviewed)abstract
- By the Schrödinger and Poisson equations, we have theoretically investigated AlGaAs/GaAs and InAlAs/InGaAs single barrier varactors. The energy band structure, carrier distribution, and conduction current are fully exploited for varactor design. We have explained the experimental current-voltage and capacitance-voltage measurements very well. A simple analytical model for energy band structure is derived based on the Schrödinger and Poisson equation calculation. It is found that a barrier structure of 3 nm Al0.3Ga0.7As/3 nm AlAs/3nm Al0.3Ga0.7As for an Al0.3Ga0.7As/GaAs varactor and a barrier structure of 8 nm In0.52Al0.48As/3 nm AlAs/8 nm In0.52Al0.48As for In0.52Al0.48As/In0.47GaAs are optimal for minimal conduction currents.
|
|
| 15. |
- Fu, Ying, 1964, et al.
(author)
-
Capacitance Analysis for AlGaAs/GaAs and InAlAs/InGaAs Heterostructure Barrier Varactor Diodes
- 1998
-
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 83:3, s. 1457-1462
-
Journal article (peer-reviewed)abstract
- By self-consistently solving Schro¨dinger and Poissons equations, we have investigated the capacitances of AlGaAs/GaAs and InAlAs/InGaAs heterostructure barrier varactors. When compared with semiclassical particle model, quantum mechanics show that the maximal capacitance of the varactor is saturated when the spacer and barrier are thin. When the spacer and barrier are very thick, both the quantum mechanics and semiconductor particle approach result in the same conclusion, namely, the maximal capacitance is inversely proportional to the sum of the spacer and barrier thicknesses. We have also shown that the maximal capacitance increases for high carrier effective mass.
|
|
| 16. |
- Fu, Ying, 1964, et al.
(author)
-
Carrier conduction through the quantum barrier in a heterostructure barrier varactor Induced by an AC-Bias
- 2000
-
In: Superlattices and Microstructures. ; 28:2, s. 135-141
-
Journal article (peer-reviewed)abstract
- By solving the time-dependent Schrodinger equation, we have studied the quantum transport of a wavepacket in a GaAs/A1GaAs heterostructure barrier varactor (HBV) diode induced by an ac bias. The current conduction of a wavepacket is complicated due to the superposition of many different stationary states. When the oscillating frequency of the external bias is relatively low, the motion of the wavepacket follows the electric field induced by the external bias. When the frequency is too high (over 1000 GHz for the GaAs/A1GaAs HBV structure under investigation), the wavepacket becomes effectively confined by the oscillating bias, and the conduction current is significantly reduced.
|
|
| 17. |
|
|
| 18. |
- Hollung, Stein, 1970, et al.
(author)
-
A 141-GHz Integrated Quasi-Optical Slot Antenna Tripler
- 1999
-
In: IEEE Antennas and Propagation Society International Symposium. - 078035639X ; 4, s. 2394-2397
-
Conference paper (peer-reviewed)abstract
- We present a quasi-optical frequency tripler with heterostructure barrier varactor (HBV) diodes soldered across two slot antennas and located at the focal plane of a dielectric lens. The slot antennas are fed from a WR-22 waveguide connected to a Gunn oscillator. A quasi-optical high-pass filter is used to tune the slot impedance and increase the conversion efficiency. The symmetric capacitance-voltage and asymmetric current-voltage characteristics of the HBV diodes only allows odd harmonics of the applied signal to be generated, and thus simplifies the frequency tripler design.
|
|
| 19. |
- Hollung, Stein, 1970, et al.
(author)
-
A 141-GHz Quasi-Optical HBV Diode Frequency Tripler
- 1999
-
In: Tenth International Symposium on Space Terahertz Technology. ; , s. 492-500
-
Conference paper (peer-reviewed)abstract
- A 141-GHz quasi-optical heterostructure barrier varactor (HBV) diode frequency tripler is presented. The tripler consists of two slot antennas loaded with FEW diodes and located at the focal plane of a dielectric lens. A quasi-optical high-pass filter is used at the output to improve the conversion efficiency and act as a tuning element for the slot antennas. The tripler demonstrates an effectively isotropic radiated power (EIRP) of 2.24 W at 141 GHz with an input power of 143 mW. The corresponding radiated power is 11.5 mW and the tripler conversion efficiency is about 8%.
|
|
| 20. |
- Hollung, Stein, 1970, et al.
(author)
-
A Distributed Heterostructure Barrier Varactor Frequency Tripler
- 2000
-
In: IEEE Microwave and Guided Wave Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1051-8207. ; 10:1, s. 24-26
-
Journal article (peer-reviewed)abstract
- We present a broadband nonlinear transmission line (NLTL) frequency multiplier at F-band. The multiplier consists of a finline section periodically loaded with 15 heterostructure barrier varactor (HBV) diodes. Tapered slot antennas are used to couple the fundamental signal from a WR-22 rectangular waveguide to the distributed multiplier as well as radiate the output power into free space. The frequency tripler exhibits 10-dBm peak radiated power at 130.5 GHz with more than 10% 3-dB bandwidth and 7% conversion efficiency. The tripler can be used as an inexpensive broad-band solid-state source for millimeter-wave applications.
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
- Ingvarson, Mattias, 1974, et al.
(author)
-
Design of Material Structures for Heterostructure Barrier Varactors
- 2001
-
In: 19th Nordic Semiconductor Meeting. ; , s. 68-
-
Conference paper (peer-reviewed)abstract
- The Heterostructure Barrier Varactor (HBV), first proposed by Kollberg et al. [1], has a symmetric C-V and an anti-symmetric I-V characteristic. Therefore it will only produce odd harmonics of the input frequency when used in mm- and submm-wave frequency multipliers, which greatly simplifies the multiplier design. The high-bandgap barriers prevent electron transport through the structure so that the depletion region of the modulation layers is controlled by the applied bias, thus modulating the capacitance of the device. By varying the number of barriers and the thickness and doping of the modulation layers, it is possible to tailor the HBV diode for various applications, e.g. power-handling capability and frequency of operation.We present four different InGaAs/InAlAs HBV materials on InP fabricated by MOVPE. Two are designed for high-power, mm-wave applications and the other two are optimised for high efficiency up to submm-wave frequencies. In order to handle high power levels, materials 1816 and 1817 have six barriers and a relatively low doping concentration which results in a high break-down voltage. The measured break-down voltage for 1817 of approximately 52 Volts for a current density of 0,1µA/µm2 is, to the best of our knowledge, the highest value reported for HBVs. Materials 1819 and 1820 have higher doping concentrations and shorter modulation layers to reduce losses and the effect of current saturation, see Table 1. Design methods and predicted RF-performance will be presented.
|
|
| 24. |
- Kollberg, Erik, 1937, et al.
(author)
-
Heterostructure Barrier Varactor Multipliers
- 1998
-
In: 2nd ESA Workshop on Millimetre Wave Technology and Applications. ; , s. 429-434
-
Conference paper (peer-reviewed)abstract
- We describe the Heterostructure Barrier Varactor (HBV) diode and its application in frequency multipliers. Different varactor models are presented that easily can be used in large signal simulations. Results from frequency multiplier measurements are presented. The delivered maximum output power at 234 GHz is 3.6 mW. Simulations show that the output power is limited by excessive conduction current due to increased diode temperature.
|
|
| 25. |
|
|
