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iii High power wideband amplifiers are demanded in many application areas, such as software defined radio, electronic warfare (EM), instrumentation systems, etc. This thesis project aims to build a high power wideband amplifier suitable for base station instrumentation purposes. It is discussed that balanced amplifiers are very suitable for this purpose due to their remarkable properties. To enable both LDMOS as well as GaN technology for true wideband operation, two bandwidth extension design methods are studied and developed within this thesis work. 3 dB quadrature couplers, which are important components in the realization of the balanced amplifiers, are demanded. In this thesis, two kinds of broadband 3-dB quadrature couplers, of which one is pretty novel, are designed and implemented. In view of lower cost of the implementation of Wilkinson dividers compared to 3-dB quadrature couplers, two broadband Wilkinson dividers are employed instead of the 3-dB quadrature couplers at the appropriate places in the total topology in order to reduce the cost and lower the complexity of the amplifier implementation. Hence, Wilkinson dividers are designed and implemented. Th