| 1. |
- Andersson, Christer, 1982, et al.
(author)
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A packaged 86 W GaN transmitter with SiC varactor-based dynamic load modulation
- 2013
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In: 43rd European Microwave Conference, EuMC 2013 - Held as Part of the 16th European Microwave Week, EuMW 2013, Nuremberg, Germany, 7-10 October 2013. - 9782874870316 ; , s. 283-286
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Conference paper (peer-reviewed)abstract
- Output power scaling based on class-J dynamic load modulation (DLM) theory is used to design an unprecedentedly high power microwave transmitter with varactor-based DLM functionality. Matching networks are realized on high dielectric constant substrates in order to reduce the form factor. The fully matched DLM PA incorporates a 24-mm GaN HEMT powerbar and a stack of four SiC varactors, all fit into a CuW package (40 mm × 20 mm). Peak output power is reconfigurable by changing the drain voltage, while retaining the DLMeffect. Under pulsed conditions at 40 V the PA delivers a peak power of 86 W at 2.14 GHz. Efficiency enhancement by DLM is 10-15 percentage-units at 6 dB output power back-off (OPBO). Employing digital predistortion (DPD) with a vector switched generalized memory polynomial (VS-GMP) the ACLR is -46 dBc at an average output power of 17 W and a drain efficiency of 34%. These results prove the potential for high output power levels in varactor-based DLM transmitters.
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| 2. |
- Andersson, Christer, 1982, et al.
(author)
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Theory and Design of Class-J Power Amplifiers With Dynamic Load Modulation
- 2012
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In: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 60:12, s. 3778-3786
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Journal article (peer-reviewed)abstract
- A theory for class-J microwave amplifier operation as a function of drive level and fundamental load impedance is derived. Calculations show that, under appropriate operating conditions, it is sufficient to modulate the transistor load reactance to enable high-efficiency operation (>70%) over a large output power dynamic range (>10 dB) with high transistor power utilization. Such dynamic load modulation (DLM) networks are an ideal application of continuously tunable varactor technologies. Multiharmonic load–pull measurements are performed on a GaN HEMT and experimentally verify the theory of operation. A demonstrator amplifier using an SiC varactor technology is then designed and characterized by static measurements. The amplifier has a peak power of 38 dBm at 2.08 GHz and maintains efficiencies above 45% over 8 dB of power dynamic range. An analysis of the load network losses is performed to show the potential of the class-J DLM transmitter concept.
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| 3. |
- Angelov, Iltcho, 1943, et al.
(author)
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On the large-signal modeling of High Power AlGaN/GaN HEMTs
- 2012
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In: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781467310871
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Conference paper (peer-reviewed)abstract
- In this paper are given some recent results on modeling of High Power GaN HEMT devices. The GaN HEMT is very promising for high power application, but we push device to the limits, so many issues are becoming critical. For example, access resistances Rs, Rd in high power GAN HEMT are bias and temperature dependent-their extraction from cold FET measurements can lead to over optimistic prediction for output power. Thermal management, self-heating modeling are another very important issue-they influence reliability, power and PAE. Models without dynamic self-heating are not practical for GaN. The models without breakdown can easily predict world records for PAE, output power/mm etc. Some examples are given using vectorial Large Signal Measurements (LSNA/NVNA) to provide useful, global info about device behavior, influence of traps, knee voltage walkout etc.
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