Siddik Yarman

3.5-3.8GHz class-E balanced GaN HEMT power amplifier with 20W Pout and 80% PAE

In this study, balanced and single ended class-E power amplifiers (PAs) were designed and realized for 3.5–3.8 GHz band by using Gallium Nitride high electron mobility transistor (GaN HEMT). Realizations were made on low loss Rogers RT5880 dielectric material which has 0.254 mm thickness and 2.2 dielectric constant. Proposed balanced class-E PA has approximately 20 W (43 dBm) output power with 80% peak power added efficiency (PAE) and shows a very favorable combination of output power, PAE and suppressed even order harmonics compared to the single ended class-E PA prototype.

Opportunistic source-pair selection (OSPS) method for multiuser Bi-directional wireless relaying networks

This paper investigates the opportunistic source-pair selection (OSPS) strategy for the co-channel interference challenge in multiuser amplify-and-forward based bi-directional wireless relaying networks. The method relies upon selection of the appropriate source-pair node among N available source-pair nodes based on each source pairs maximum sum capacity. According to the simulation results, the OSPS strategy, besides achieving the near optimal solution for the co-channel interference challenge, and if the number of the user pair increases, also achieves multiuser diversity order by selecting the maximum sum-capacity user-pair in each time slot.

Broadband Equalizer Design with Commensurate Transmission Lines via Reflectance Modeling

In this paper, an alternative approach is presented, to design equalizers (or matching networks) with commensurate (or equal length) transmission lines. The new method automatically yields the matching network topology with characteristic impedances of the commensurate lines. In the implementation process of the new technique first, the driving point impedance data of the matching network is generated by tracing a pre-selected transducer power gain shape, without optimization. Then, it is modelled as a realizable bounded-real input reflection coefficient in Richard domain, which in turn yields the desired equalizer topology with line characteristic impedances. This process results in an excellent initial design for the commercially available computer aided design (CAD) packages to generate final circuit layout for fabrication. An example is given to illustrate the utilization of the new method. It is expected that the proposed design technique is employed as a front-end, to commercially available computer aided design (CAD) packages which generate the actual equalizer circuit layout with physical dimensions for mass production.

Multiband matching network design via transformation based Real Frequency Approach

In this paper, a new method is presented for multiband matching network design. Low pass to band pass (LP-BP) frequency transformation is incorporated with the parametric Real Frequency Technique (RFT) for creating multiband network functions. In the new parametric approach, the poles of a low pass type impedance function are optimized under LP-BP transformation, for multiband matching of complex terminations. The resultant matching network is realized with resonance sections yielding multiband transducer power gain (TPG) characteristic.

Impact of the External Co-channel Interferences Over Multiuser Bi-directional Wireless Relaying Networks-Part I: System Description and Outage Analysis

This paper investigates the impact of co-channel interferences (CCIs) caused by the external terminals over multiuser bi-directional amplify-and-forward (AF) relaying. The investigation considers multiuser pair and single bi-directional AF based relay and finite numbers of external interference terminals in the system model. Simultaneous transmission model, which is default mode, creates CCIs that is caused by the other user-pairs (internal terminals) in the system model. The opportunistic source-pair selection (OSPS) strategy achieves near-optimal solution for the internal CCIs challenge and also achieves diversity order in high SNR regimes. However, external terminals’ CCIs are inevitable and degrades the system performance. The main aim of this paper is to clearly state the impacts of external CCIs both for simultaneous and OSPS methods. According to the simulation results, in the case that the external terminals’ transmit powers are identical and non-identical to each other, and if the external terminals’ transmit powers are proportional with SNR, this results on the degradation of the achievable diversity order from

Dual band matching network design via real frequency technique by mapping from a band pass prototype

N

Design of impedance matching network for B&K 8104 hydrophone via Direct Computational Technique for underwater communication

N to 0 while also affecting the coding gain. The results also show that, when the external terminals have fixed transmit power values rather than proportional with SNR, in this circumstance, external terminals interference does not affect the achievable diversity order but it affects the system coding gain.The results also show that, when the number of external terminals which affect the user-pairs and relay terminals increase, for both identical and non-identical cases, the losses at the system coding gain exponentially decay. On the other hand, if the external terminals have non-identical transmit powers and if the relay terminal is interfered with more transmit power in comparison with what interferes with the user-pairs, this gives better performance values.

A frequency transformation based real frequency design approach for dual-band matching

A high efficient GaN HEMT power amplifier with a new topology is presented for to be used at 3.4-3.7 GHz band. Short sections of the Microstrip-lines are used as harmonic traps at the load network in order to improve the efficiency. The fabricated GaN HEMT amplifier delivers 37.5 dBm saturated output power and the maximum power-added efficiency of 80% and a maximum drain efficiency of 83% are obtained at 3.6 GHz. These values represent the state-of-the-art performance efficiencies at S-Band.