@phdthesis{Le2024, author = {Le, Quang Huy}, title = {Empirical large-signal modeling of 22-nm FDSOI CMOS transistors in RF/mm-Wave range}, doi = {10.26127/BTUOpen-6807}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-68077}, school = {BTU Cottbus - Senftenberg}, year = {2024}, abstract = {In recent years, the deployment of the 5th generation (5G) telecommunications network has fuelled growing interest in low-power and low-cost wireless transceivers in the radio frequency integrated circuits (RFIC) market. With silicon-based complementary- metal-oxide-semiconductor (CMOS) technologies, the digital circuitries and the RF front-end can be implemented monolithically as a single system-on-chip (SoC). In such scenario, advanced fully depleted silicon-on-insulator (FDSOI) technology has emerged as a potential candidate to meet the market demand. In particular, the industry's 22-nm FDSOI technology has been continuously matured in accordance with the development roadmap for 5G mm-wave applications. Research in transistor device modeling is of high importance to support the technology development process. Moreover, a large-signal model that accurately captures and reflects the transistor's nonlinear behaviour is essential for circuit design and reliability analysis. Hence, this thesis deals with measurement-based approach, i.e., empirical modeling, to develop a suitable large-signal model for the mm-wave transistors in 22-nm FDSOI technology platform. A versatile and efficient large-signal model based on the Angelov (Chalmers) model is proposed in this work. Besides, artificial neural network (ANN) is utilized to model the gate charge of the transistors. Moreover, the systematic modeling procedure addresses many important issues to ensure good model-to-hardware correlation. The proposed model is well validated for small-signal operation up to 110 GHz. Furthermore, by means of non- 50-Ω large-signal measurements, the excellent model validity to predict the nonlinear distortions of the FDSOI transistors is also comprehensively demonstrated. Finally, to evaluate the model applicability in RF circuit design, the proposed model is implemented in a commercial circuit simulator for the design of a wideband 22-nm FDSOI power amplifier.}, subject = {mm-wave; 22-nm; FDSOI; CMOS; ANN; Large-signal model; KNN; Großsignalmodell; mm-Wellen; Modellierung; Großsignalverhalten; Transistor; SOI-Technik; CMOS-Schaltung; Milimeterwelle; 5G}, language = {en} } @phdthesis{Kared2025, author = {Kared, Trusha}, title = {Mathematical analysis, design, and validation of a high dynamic range, low noise differential mixer using SiGe microwave transistors}, doi = {10.26127/BTUOpen-7121}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-71216}, school = {BTU Cottbus - Senftenberg}, year = {2025}, abstract = {The limits imposed by the wireless environment require the designer to consider noise, linearity, and power consumption. Bipolar technology has been the most appealing silicon technology due to its high-speed performance and well-engineered base parasitics. Its high transition frequency and low base resistance have resulted in remarkable noise performance. These advantages, combined with scaling flexibility, have made bipolar devices the fundamental component of silicon RF front-ends. With the growing demand for high-performance wireless applications from satellite and radar systems to 5G infrastructure, there is a strong need for advanced mixer architectures that can deliver high isolation, gain, and low noise across wide frequency ranges. The purpose of this dissertation was to describe the differential mixer and its mathematical properties in terms of gain and noise figure, and to explore further optimizations. In fact, it turned out that the mixer design was greatly improved in terms of both the noise figure and the intercept point. The active double-balanced down-conversion mixer is built on SiGe technology. The circuit exhibits significant improvement in terms of the mixer's other performance parameter metrics. This dissertation presents a novel SiGe HBT-based differential double-balanced down-conversion mixer featuring significantly enhanced conversion gain, noise performance, linearity, dynamic range, and port-to-port isolation. Compared to existing designs, this mixer delivers outstanding performance, achieving a single-sideband (SSB) noise figure of 7 dB ± 0.4 dB, a conversion gain of 12 dB ± 1 dB, and exceptional isolation metrics RF-to-IF isolation greater than 35 dB, with LO-to-RF and LO-to-IF isolation exceeding 50 dB across the 0.5 GHz to 1.8 GHz frequency range. Furthermore, it has an Input third-order intercept point (IP3) of +4.7 dBm, an output third-order intercept point (OIP3) of +15 dBm, and a 1 dB compression point of -8 dBm. This high-performance down-conversion double-balanced mixer integrates several state-of-the-art innovations. A transformer-free single-ended-to-differential conversion enhances efficiency and eliminates unnecessary components at the RF stage. The dual-feedback linearization technique optimizes impedance matching while suppressing nonlinear distortion, ensuring superior linearity. Additionally, symmetrical active device layout and advanced multilayer PCB technology significantly mitigate LO-to-RF feedthrough, reducing crosstalk and maximizing port-to-port isolation. These advancements collectively result in a highly efficient, low-noise, and exceptionally linear mixer architecture, setting a new benchmark in SiGe HBT-based mixer technology rather than relying on noisy CMOS technology. Due to its higher fabrication complexity, lower yield at advanced nodes, and the necessity for more complicated design tactics in high-frequency applications, CMOS technology in small quantities is ultimately more costly than SiGe HBT-based designs. Although CMOS excels in low-power applications and large-scale digital integration, SiGe HBT remains a reasonably affordable option for high-performance RF}, subject = {Down-conversion double balanced mixer; Noise figure; Dynamic range; Marchand balun; LO mixing core; Doppelt balancierter Abw{\"a}rtsmischer; Rauschmaß; Dynamikbereich; Marchand-Balun; LO-Mischkern; Heterobipolartransistor; Siliciumhalbleiter; Germaniumlegierung; Mischer ; Rauschmessung}, language = {en} } @phdthesis{Beleniotis2025, author = {Beleniotis, Petros}, title = {Physics-based trap modeling of GaN HEMTs}, doi = {10.26127/BTUOpen-6933}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-69331}, school = {BTU Cottbus - Senftenberg}, year = {2025}, abstract = {Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) have emerged as the preferred choice for telecommunication system designs, owing to their superior power levels compared to their silicon counterparts, especially at high frequencies and in harsh environments. Despite these advantages, reliable GaN HEMTs have been impeded by challenges such as electron trapping, which significantly impairs transistor functionality. Accurately modeling these effects is essential for the successful deployment of GaN-based designs. Over the past 15 years, the focus has been on empirical models suitable for circuit design. These models often result in a disconnect between modeling and technological advancements, thereby limiting further optimization of device performance. This study presents a novel trap model for GaN HEMTs that combines accuracy with physical principles. The model is broadly applicable, enabling the simulation of current collapse and knee walkout under various bias conditions, and is adaptable to RF applications with exceptional accuracy, through different trap-circuit configurations. The first model configuration is effective in simulating small- and large-signal continuous-wave (CW) RF measurements. It accurately mimics the slow response of electrons in traps to voltage reductions, ensuring efficient performance in simulations where traps maintain a steady state. Its accuracy has been validated through multiple measurements, including pulsed IV, S-parameter measurements, RF power sweeps, and load pull contours. Its development was enhanced by integrating experimental data and theoretical insights, which improved its accuracy and facilitated the development of additional analytical tools, such as statistical and compact modeling for trap localization. The second configuration is advantageous for pulsed RF and switching applications, as well as high-temperature environments. This configuration enables precise characterization of the swift capture time constant, a capability previously unattainable with conventional measurement techniques. Its development followed a systematic approach, beginning with the characterization of trap levels within the band gap of the devices, followed by the application of TCAD simulations to locate the position of traps and assess their impact on device performance. Ultimately, the second trap model configuration incorporates Shockley-Read-Hall (SRH) statistics to model temperature- and bias-dependent trapping, aiming to simulate the slow gate-induced trapping observed in rugged GaN-based low-noise amplifiers (LNAs). The inclusion of SRH statistics addresses significant challenges in GaN HEMT trap modeling.}, subject = {Shockley-Read-Hall; GaN HEMT; Microwaves; Compact models; Trapping effects; Mikrowellen; Kompaktmodelle; Trapping-Effekte; HEMT; Galliumnitrid; Mikrowelle; Modellierung; Elektron}, language = {en} } @phdthesis{Kaule2023, author = {Kaule, Evelyne}, title = {Robuste rauscharme GaN Verst{\"a}rker : Untersuchung und Limitierung der Ausgangsleistung im {\"U}berlastfall}, doi = {10.26127/BTUOpen-6603}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-66035}, school = {BTU Cottbus - Senftenberg}, year = {2023}, abstract = {Stetig steigende Leistungen der Leistungsverst{\"a}rker in den Sender-Empf{\"a}ngermodulen zwingen den rauscharmen Verst{\"a}rker zu einem immer h{\"o}heren Schutz am Eingang. Aufgrund hoher Durchbruchspannungen bieten GaN HEMTs eine robuste Eingangsstufe, womit ein Schutz des LNA Eingangs und die damit verbundene Verschlechterung der Rauschzahl unn{\"o}tig wird. Allerdings n{\"u}tzte dieser Schutz nicht allein den rauscharmen Verst{\"a}rker, da nachfolgende Stufen durch die hohen Ausgangsleistungen der GaN LNAs zerst{\"o}rt werden k{\"o}nnen. Daher widmet sich diese Arbeit der Untersuchung von robusten rauscharmen GaN Verst{\"a}rkern sowie verschiedener Schaltungen zum Schutz der nachfolgenden Stufen vor einer zu hohen Eingangsleistung, wobei die Rauschzahl unbeeinflusst bleiben soll. Da eine robuste Eingangsstufe relevant f{\"u}r diese Arbeit ist, wurden neuartige Designs von robusten GaN LNA MMIC untersucht. Einerseits wurde ein LNA MMIC Chip mit einer gestapelten Eingangsstufe entwickelt, womit die Eingangsleistung und entsprechend die Robustheit erh{\"o}ht werden konnte. In dieser Arbeit wird ein verbessertes Design des gestapelten GaN LNA MMIC vorgestellt, dessen Verst{\"a}rkung von mehr als 23 dB und ein Rauschmaß von 2,6 dB im C-Band Frequenzbereich erreicht. Anderseits wurde ein neuartiger multiband GaN LNA MMIC f{\"u}r die Frequenzen 0,8 GHz; 1,8 GHz und 3,6 GHz entwickelt. Dieser erreicht eine Verst{\"a}rkung von mehr als 29 dB bei 0,8 GHz und mehr als 34 dB bei 3,6 GHz mit einer maximalen Verst{\"a}rkung von 34,9 dB bei 1,8 GHz sowie einen minimalen Rauschmaß von 2,2 dB bei 3,6 GHz. Der multiband LNA MMIC ist mit einen OIP3 von mehr als 36dBm bei 3,6 GHz hochlinear. Weiterhin wurde f{\"u}r den gestapelten und den multiband GaN LNA MMIC die Robustheit mittels eines hochohmigen Widerstands in der Gate Versorgung verbessert. Im Rahmen der Charakterisierung von GaN Verst{\"a}rkern zeigt sich, dass der Gate DC und Drain DC Strom Indikatoren jeweils f{\"u}r die Kompression und S{\"a}ttigung der Ausgangsleistung im {\"U}berlastfall darstellen. Der Zusammenhang zwischen dem Gate DC Strom und dem {\"U}berlastfall war der Ausgangspunkt f{\"u}r die Entwicklung der Schaltungen zur Limitierung der Ausgangsleistung, um die nachfolgenden Stufen des LNAs zu sch{\"u}tzen. Daher wird dieser Strom zum Schalten eines Ausgangsd{\"a}mpfungsglieds sowie einer adaptiven Drain DC Versorgung verwendet. Das Ausgangsd{\"a}mpfungsglied wurde als ein GaN HEMT in Common-Gate Konfiguration an den Ausgang eines robusten GaN LNAs auf einen Chip geschalten, wodurch im {\"U}berlastfall eine D{\"a}mpfung von 29 dB erreicht wird. Weiterhin konnte durch die adaptive Drain DC Versorgung, welche als eine hybride Schaltung mit einem robusten GaN LNA MMIC als Kern entwickelt wurde, eine D{\"a}mpfung von 28 dB erzielt werden. Sowohl f{\"u}r das Ausgangsd{\"a}mpfungsglied als auch f{\"u}r die adaptive Drain DC Versorgung blieben die Kleinsignal Verst{\"a}rkung und das Rauschmaß des GaN LNA MMICs unbeeinflusst.}, subject = {GaN; HEMT; Rauscharmer Verst{\"a}rker; Robustheit; {\"U}berlastfall; MMIC; Galliumnitrid; HEMT; Rauscharmer Verst{\"a}rker; Robuste Regelung; {\"U}berlastkontrolle; Low-noise amplifier; LNA; Ruggedness; Overdrive condition}, language = {de} } @phdthesis{TomazdeCarvalho2024, author = {Tomaz de Carvalho, Antonio}, title = {A novel system for characterization of GaN-based low-noise amplifiers}, doi = {10.26127/BTUOpen-6844}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-68446}, school = {BTU Cottbus - Senftenberg}, year = {2024}, abstract = {Although low-noise amplifiers (LNA) are designed to amplify low RF power levels, there are possibilities that they receive high RF powers as front-end radios and electronic warfare receiver systems. Commonly, this high power levels are not desired. Due to such applications and demands, robust LNA are required. The GaN-based HEMT low-noise amplifiers are being considered an established technology used on different applications for telecommunications systems and radars. The GaN-based LNAs can handle high RF input powers, and they still keep functional. These GaN-based robust LNAs have several advantages, as no limiters are required to protect them against high RF input powers. As a result, these robust LNAs have a simplified RF receiver architecture and are cheaper to manufacture. However, the GaN HEMTs LNAs are known to show significant memory effects, which also play a negative role when a high RF input power level is received by the LNA and drives it into compression. After degradation of the LNA performance, it needs time to recover to its normal small-signal operation mode. This time is called recovery time. This is an important measurement parameter, once some applications require receivers to work immediately after a high RF input power was received, especially for pulse-radar applications. The main focus of this thesis is on the implementation of a novel measurement setup suitable to characterize the GaN-based robust LNAs and their recovery time. First, the system concept was implemented step by step using different instruments. The whole system setup has been programmed to work remotely, to perform the measurement and to save the results automatically. A software based on Matlab script language was developed and integrated to the system setup in order to control the test equipment. The setup allows for simultaneous measurements and data acquisitions. The setup can perform recovery time measurements in time domain, can measure the reflected power and also monitor the drain current of the LNA. A pulse signal is used as overdrive signal to stress the LNA with high-power levels, which can be variously defined in width and period according to the target application. This overdrive signal can also be monitored and measured during the recovery time characterization. The core of the measurement system is an PNA-X vector network analyzer, which allows the characterization of small-signal gain recovery time. The reflected power is measured using a power sensor, while the drain current is monitored using an oscilloscope. In order to validate the system setup, three different GaN LNAs were used. Finally, the system was extended to work also for 5 GHz frequency band. The results shown in this thesis enables for innovative future research activities on robust LNAs.}, subject = {Amplifier; LNA; Robust; GaN; Microwave; Rauscharmer Verst{\"a}rker; Robustheit; {\"U}berlastfall; MMIC; RF und Mikrowellentechnik; MMIC; Rauscharmer Verst{\"a}rker; Galliumnitrid; HEMT; {\"U}berlast}, language = {en} } @phdthesis{Fleischmann2022, author = {Fleischmann, Manfred}, title = {A novel technique to improve the spurious-free dynamic range of digital spectrum monitoring receivers}, doi = {10.26127/BTUOpen-5898}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-58984}, school = {BTU Cottbus - Senftenberg}, year = {2022}, abstract = {This dissertation presents a novel technique for enhancing the spurious-free dynamic range of radio monitoring receivers with a bandwidth of several gigahertz. The improvement is based on suppressing the discrete spurious signals that occur at higher drive levels in the output spectrum of the required broadband analog-to-digital converter. The achievable improvement of the spurious-free dynamic range is typically more than 20 dB, allowing better, gap-free monitoring of wide frequency ranges. The attenuation of the spurious signals is achieved by a unique combination of two separate analog-to-digital converters working in parallel and subsequent digital signal processing. The developed solution is not limited to broadband radio monitoring receivers but can generally suppress certain types of spurious signals generated during analog-to-digital conversion.}, subject = {Broadband receiver; Spurious signals; Analog-to-digital converter; Spurious-free dynamic range; Digital signal processing; Breitbandempf{\"a}nger; St{\"o}rsignale; Analog-digital-Wandler; St{\"o}rungsfreier Dynamikbereich; Digitale Signalverarbeitung; Analog-Digital-Umsetzer; Breitbandempf{\"a}nger; Digitale Signalverarbeitung; St{\"o}rsignal}, language = {en} }