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Yayın On numerical design technique of wideband microwave amplifiers based on GaN small-signal device model(Springer, 2014-10) Köprü, Ramazan; Kuntman, Hulusi Hakan; Yarman, Bekir Sıddık BinboğaThis work presents an application of Normalized Gain Function (NGF) method to the design of linear wideband microwave amplifiers based on small-signal model of a device. NGF has been originally developed to be used together with an S-parameter (*.s2p) file, whereas this work enables the NGF to be able to work with explicit S-parameter formulae derived from the small-signal model of the device. This approach provides the designer to be able to use simple set of S-parameter equations instead of S-parameter file of the device. Representation of the device simply by several model equations not only eliminates the need of carrying large number of data but also provides the capability of equation-based easy, realistic and equispaced S-parameter data generation in any desired resolution in frequency axis without requiring interpolation. NGF is defined as the ratio of T and |S-21|(2), i.e. T-N = T/|S-21|(2), gain function of the amplifier to be designed and transistor forward gain function, respectively. Synthesis of output/input matching networks (OMN/IMN) of the amplifier requires two target gain functions in terms of T-N, to be used in two sequential non-linear optimization procedures, respectively. An amplifier with a flat gain of similar to 10 dB operating in 0.8-2.35 GHz is designed using a small-signal model of an experimental GaN-HEMT. Theoretical amplifier performance obtained in Matlab is shown to be in excellent agreement with the simulated performance in MWO (Microwave Office, AWR Inc.). A prototype low-power amplifier having a similar to 10 to 12 dB gain, operating in (0.9-1.5 GHz) is also produced and measured which yielded good performance results.Yayın Design of a new low loss fully CMOS tunable floating active inductor(Springer New York LLC, 2016-12) Momen, Hadi Ghasemzadeh; Yazgı, Metin; Köprü, Ramazan; Saatlo, Ali NaderiIn this paper, a new tunable floating active inductor based on a modified tunable grounded active inductor is proposed. The multi regulated cascade stage is used in the proposed active structure to decrease the parasitic series resistance of active inductor, thus the Q factor enhancement is obtained. Furthermore, the arrangement of this stage leads to the smaller input transistor which determines active inductor’s self-resonance frequency and to be free of body effect which is crucial in sub-micron technology. Symmetrical design strategy has enabled both ports of the proposed floating active inductor to demonstrate the same properties. The Q factor and active inductor value are tuned with bias current and flexible capacitance (varactor), respectively. The self-resonance frequency of floating active inductor (~6.2 GHz) is almost the same as grounded prototype. In addition, the proposed active inductor also shows higher quality factor and inductance value compared to the conventional floating active inductor circuits. To show the performance of suggested circuit, simulations are done by using a 0.18 µm CMOS process, which demonstrates an adjustable quality factor of 10–567 with an inductance value range of 6–284 nH. Total DC power consumption and occupied area are 2 mW and 934.4 µm2, respectively.Yayın A design technique of 50 Ω terminated bandpass matching network and its implementation to a Y-shaped monopole antenna matching(Springer, 2016-12) Aydın, Çağatay; Atilla, Doğu Çağdaş; Köprü, Ramazan; Kılınç, Sedat; Karakuş, Cahit; Yarman, Bekir Sıddık BinboğaIn this paper, a 50 Ω terminated or in other words transformerless bandpass matching network design methodology and an implementation example are presented. The real frequency techniques are powerful numerical methods to design wideband lossless two-port networks such as filters, matching networks and amplifiers. In these techniques, the value of the termination resistance of the designed network could not be yielded as 50 Ω by numerical package. Hence, a transformer is also required for 50 Ω termination which is not practical for high frequency applications. By employing the proposed procedure, it is guaranteed to obtain transformerless bandpass matching network. Also in this study a wideband suspended monopole antenna is examined. The proposed antenna consists of two major elements; Y-shaped impedance matching plate and hemi-circular radiator. Moreover Y-shaped impedance matching plate connected to a feeding probe excites the suspended hemi-circular radiator via air gap. Consequently, a transformerless bandpass matching network is designed to filter and expand the operational frequency bandwidth of the proposed antenna. It has been observed that ideal circuit and the layout of the matching network simulation have good agreement.Yayın Ultra wideband matching network design for a V-shaped square planar monopole antenna(Cambridge University Press, 2014-12) Köprü, Ramazan; Kılınç, Sedat; Aydın, Çağatay; Atilla, Doğu Çağdaş; Karakuş, Cahit; Yarman, Bekir Sıddık BinboğaIn this paper, design, manufacture, and measurement of a wideband matching network for a broadband V-shaped square planar monopole antenna (V-SPMA) is presented. Matching network design is unavoidable in most cases even vital to facilitate a maximally flat power transfer gain for an antenna. In the work, a bandpass matching network (BPMN) design is done for a particular square monopole antenna with V-shaped coupling element that has essentially bandwidth increasing effect. Designed BPMN and the antenna forms a VSPMA-BPMN matched antenna structure. "real frequency technique" is employed in the BPMN design. BPMN prototype circuit has been constructed on an FR4 laminate with commercial microwave chip inductors and capacitors. Vector network analyzer gain and reflectance measurements of the matched antenna structure have shown highly compatible results to those of the theoretical design simulations along the passband (similar to 0.8-4.7 GHz). Furthermore, newly proposed distributed capacitor-resistor lossy model for microstrip lines used in the BPMN circuit have exhibited that it can successfully mimic the measured gain and reflectance performance of the matched structure in passband and even in stopband upto 8 GHz. Designed structure can be utilized as a one single wideband broadcasting medium suitable for many communication standards such as GSM, 3G, and Wi-Fi.Yayın Termination transformation theorem for microwave power transfer networks(World Scientific Publishing Co. Pte Ltd, 2020-03-15) Köprü, RamazanTermination transformation theorem (TTT) proposed in this work transforms a doubly complex terminated microwave power transfer network (PTN) to an equivalent doubly resistively terminated termination transformed network (TTN) which is essentially a filter network. In this work, the transducer power gain (TPG) formula, Tgen, based on S and transmission (ABCD) parameters for the PTN have been restudied from the classical literature. Then, a new TPG formula, Tgen1, based on the newly proposed TTT has been derived using the transformed TTN network. To be able to show the validity of the proposed TTT, the newly derived TPG formula Tgen1 and the classical TPG formula Tgen have been computed within the scope of an example PTN design. The theorem has been proved mathematically, and experimentally as well with the aid of a Matlab code. The performance plots yielded from the Matlab code have clearly shown that both TPG formulae, i.e., Tgen and Tgen1, are in complete agreement with each other. In that sense, the proposed TTT might be considered as an alternative and helpful technique to be used in microwave engineering.Yayın Novel approach to design ultra wideband microwave amplifiers: Normalized gain function method(Spolecnost Pro Radioelektronicke Inzenyrstvi, 2013-09) Köprü, Ramazan; Kuntman, Hulusi Hakan; Yarman, Bekir Sıddık BinboğaIn this work, we propose a novel approach called "Normalized Gain Function (NGF) method" to design low/medium power single stage ultra wide band microwave amplifiers based on linear S parameters of the active device. Normalized Gain Function T-NGF is defined as the ratio of T and vertical bar S-21 vertical bar(2), desired shape or frequency response of the gain function of the-amplifier to be designed and the shape of the transistor forward gain function, respectively. Synthesis of input/output matching networks (IMN/OMN) of the amplifier requires mathematically generated target gain functions to be tracked in two different nonlinear optimization processes. In this manner, NGF not only facilitates a mathematical base to share the amplifier gain function into such two distinct target gain functions, but also allows their precise computation in terms of T-NGF=T/vertical bar S-21 vertical bar(2) at the very beginning of the design. The particular ainplifier presented as the design example operates over 800-5200 MHz to target GSM, UNITS,. Wi-Fi and WiMAX applications. An SRFT (Simplified Real Frequency Technique) based design example supported by simulations in MWO (Micro Wave Office from AWR Corporation) is given using a 1400 mW pHEMT transistor, TGF2021-01 from TriQuint Semiconductor.Yayın Low-loss active inductor with independently adjustable self-resonance frequency and quality factor parameters(Elsevier Science BV, 2017-06) Köprü, Ramazan; Momen, Hadi Ghasemzadeh; Yazgı, Metin; Saatlo, Ali NaderiThis work presents a new low-loss active inductor whose self-resonance frequency and quality factor parameters can be adjusted independently from each other. In order to achieve this property, a new input topology has been employed which consists of cascode structure with a diode connected transistor. Furthermore, the proposed input topology makes the device robust in terms of its performance over variation in process, voltage and temperature. Additionally, RC feedback is used to cancel series-loss resistance of the active inductor, which allows self-resonant enhancement as well. Schematic and post-layout simulation results show the theoretical validity of the design. To validate the design feasibility for process, voltage and temperature changes, Monte Carlo and temperature analysis are done. Suggested structure shows inductor behavior in the frequency range of 0.3–11.3 GHz. Maximum quality factor is obtained as high as 2.1k at 5.9 GHz. Total power consumption is as low as 1 mW with 1.8 V power supply.
