| 1. |
- Andersson, Christer, 1982, et al.
(författare)
-
Nonlinear Characterization of Varactors for Tunable Networks by Active Source-Pull and Load-Pull
- 2011
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 59:7, s. 1753-1760
-
Tidskriftsartikel (refereegranskat)abstract
- Varactors are key components in the realization of tunable networks, for instance, in high-efficiency power-amplifier architectures. This paper presents a method to measure the varactor quality factor (Q-factor) in the presence of nonlinear distortion. The importance of correctly choosing the loading condition at the second harmonic is illustrated by multiharmonic active source- and load-pull measurements. Furthermore, the method also allows for accurate extraction of the bias-dependent series resistance without the need of area consuming resonant structures. The proposed method is applied to characterize a silicon-carbide (SiC) Schottky diode varactor at 3 GHz. The measured results reemphasize that varactors are not linear tunable, but inherently nonlinear components that require proper consideration of the higher order harmonics.
|
|
| 2. |
- Angelov, Iltcho, 1943, et al.
(författare)
-
On the large-signal modeling of High Power AlGaN/GaN HEMTs
- 2012
-
Ingår i: IEEE MTT-S International Microwave Symposium Digest. - 0149-645X. - 9781467310871
-
Konferensbidrag (refereegranskat)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.
|
|
| 3. |
- Frank, Markus, 1970, et al.
(författare)
-
Differential Impedance Measurement Method of RFID Transponder Chips at UHF
- 2013
-
Ingår i: Proceedings of the 43rd European Microwave Conference. - 9782874870316 ; 2013, s. 68-71
-
Konferensbidrag (refereegranskat)abstract
- A novel on-wafer measurement method of RFID transponder chips is presented. A comparison is made between single ended one-port, single ended two-port and differential two-port excitation. The two-port method is a flexible way of measuring chips consisting of both several individuals as well as chip types with different geometries with one and the same probe type. The theory of un-terminating and de-embedding is described and verified by measurements. A qualitative analysis is defined, which explains certain phenomena seen in communication tests performed on RFID protocol level. This is further supported by measurement results from the presented method.
|
|
| 4. |
- Prasad, Ankur, 1987, et al.
(författare)
-
Symmetrical Large-Signal Modeling of Microwave Switch FETs
- 2014
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 62:8, s. 1590-1598
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new symmetrical field-effect transistor (FET) model suitable for microwave switches. The model takes advantage of the inherent symmetry of typical switch devices, justifying a new small-signal model where all intrinsic model parameters can be mirrored between the positive and negative drain-source bias regions. This small-signal model is utilized in a new and simplified approach to large-signal modeling of these type of devices. It is shown that the proposed large-signal model only needs a single charge expression to model all intrinsic capacitances. For validation of the proposed model, small-signal measurements from 100 MHz to 50 GHz and large-signal measurements at 600 MHz and 16 GHz, are carried out on a GaAs pHEMT. Good agreement between the model and the measurements is observed under both small-and large-signal conditions with particularly accurate prediction of higher harmonic content. The reduced measurement requirements and complexity of the symmetrical model demonstrates its advantages. Further, supporting operation in the negative drain-source voltage region, the model is robust and applicable to a variety of circuits, e. g., switches, resistive mixers, oscillators, etc.
|
|
| 5. |
- Prasad, Ankur, 1987, et al.
(författare)
-
Symmetrical modeling of GaN HEMTS
- 2014
-
Ingår i: Technical Digest - IEEE Compound Semiconductor Integrated Circuit Symposium, CSIC. - 1550-8781. - 9781479936229
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a symmetrical small signal model for GaN HEMTs valid for both positive and negative Vds. The model takes advantage of the intrinsic symmetry of the devices typically used for switches. The parameters of the model are extracted using a new symmetrical optimization based extraction method, optimizing simultaneously for both positive and negative drain-source bias points. This ensures a symmetrical small signal model with lower modeling error. The small signal model can be further used to simplify the development of a large-signal model. The small signal model is validated with measured S- parameters of a commercial GaN HEMT.
|
|
| 6. |
- Sudow, Mattias, 1980, et al.
(författare)
-
A Single-Ended Resistive $X$-Band AlGaN/GaN HEMT MMIC Mixer
- 2008
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 56:10, s. 2201-2206
-
Tidskriftsartikel (refereegranskat)abstract
- A broadband highly linear X-band mixer in AlGaN/GaN monolithic microwave integrated circuit technology has been designed, processed, and characterized. The design is based on a 4 times 100 mum AlGaN/GaN HEMT in a single-ended circuit topology. The mixer has an IF bandwidth of 2 GHz with a conversion loss (CL) of
|
|
| 7. |
- Sudow, Mattias, 1980, et al.
(författare)
-
An AlGaN/GaN HEMT-Based Microstrip MMIC Process for Advanced Transceiver Design
- 2008
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 56:8, s. 1827-1833
-
Tidskriftsartikel (refereegranskat)abstract
- A MMIC process in AlGaN/GaN technology for advanced transceiver design has been developed. The process is based on microstrip technology with a complete model library of passive elements and AlGaN/GaN HEMTs. The transistor technology in this process is suitable for both power and low noise design, demonstrated with a power density of 5 W/mm, and an ${rm NF}_{min}$ of 1.4 dB at $X$ -band. Process stability of subcircuits, complementary to power amplifiers and LNAs, in a transceiver system have been investigated. The results indicate that an all AlGaN/GaN MMIC transceiver is realizable using this technology.
|
|
| 8. |
- Sudow, Mattias, 1980, et al.
(författare)
-
SiC varactors for dynamic load modulation of high power amplifiers
- 2008
-
Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 29:7, s. 728-730
-
Tidskriftsartikel (refereegranskat)abstract
- SiC Schottky diode varactors with a high breakdown voltage, a high tuning ratio, and a low series resistance have been designed and fabricated. These characteristics are particularly necessary for the dynamic load modulation of high power amplifiers (PAs), which is an attractive alternative to other efficiency enhancement techniques. For a SiC Schottky diode varactor with a 50-µm radius fabricated by using a graded doping profile, a breakdown voltage of 40 V, a tuning range of 5.6, and a series resistance of 0.9 O were achieved. The results show the great potential of this type of varactors for the use in the dynamic load modulation of high power amplifiers. © 2008 IEEE.
|
|
| 9. |
- Thorsell, Mattias, 1982, et al.
(författare)
-
Characterization of the temperature dependent access resistances in AlGaN/GaN HEMTs
- 2008
-
Ingår i: Workshop on Integrated Nonlinear Microwave and Millimetre-Wave Circuits, 2008. INMMIC 2008.. - 9781424426454 ; , s. 17-20
-
Konferensbidrag (refereegranskat)abstract
- The temperature dependence of the access resistances for AlGaN/GaN HEMTs is investigated. The self-heating is measured using infrared microscopy and the access resistances are extracted at different ambient temperatures. Their influence on the intrinsic small signal parameters is studied versus bias and ambient temperature.
|
|
| 10. |
- Thorsell, Mattias, 1982, et al.
(författare)
-
Thermal characterization of the intrinsic noise parameters for AlGaN/GaN HEMTs
- 2008
-
Ingår i: International Microwave Symposium Digest, 2008, Atlanta. - 0149-645X. - 9781424417810 ; , s. 463-466
-
Konferensbidrag (refereegranskat)abstract
- The noise parameters of AlGaN/GaN-HEMTs are measured between 298 K and 423 K. The temperature dependent access resistances are de-embedded and the intrinsic noise parameters are studied as a function of temperature. It is shown that the parasitic access resistances are limiting the highfrequency noise performance of the AlGaN/GaN-HEMT.The intrinsic noise sources are extracted and a noise model is derived and verified for a MMIC amplifier.
|
|
