Increasing demand to provide higher data rates with spectral purity sets high standards for future mobile communication systems. Future wireless communication transmitters are challenged to improve their performance with reduced power consumption. Work performed in this thesis aims at improving several key areas of a wireless transmitter architecture to be more efficient and reliant on their power consumption. A novel calibration technique based on constellation mapping of a quadrature amplitude modulated (QAM) signal is proposed to alleviate the analog impairments within a wireless transmitter at system level. This technique facilitates the mixed-signal approach towards building efficient, linear transmitters. A primary front-end component of a wireless transmitter is the Power Amplifier (PA). Advanced architectures for PAs with improved power efficiency need to be explored for these future wireless communication systems. Ameliorations made towards improving the hardware structure in literature provides a variety of advanced power amplifier architectures. In analyzing the needs for the future mobile communication standards, and the complex nature of the signals involved, the Doherty power amplifier (DPA) architecture has indicated promise over the years. In this work, further improvements have been made on existing state-of-the-art Doherty PA architectures to aid wider-bandwidth operation to transmit at higher data rates. A distributed structure of four-way digitally controlled inputs has been suggested and its operation was tested at Ku-band frequency range. Furthermore, in simulating advanced PA architectures such as mentioned above, the time taken to perform a single simulation for a PA is significant. As a result, in-order to perform a system level simulation of a transmitter with several PA’s and other components will be even more apparent and less convenient. Therefore, for futuristic applications such as distributed arrays, a method of behavioral modeling of a fabricated asymmetrical DPA is suggested and tested.