Fourth generation (4G) wireless mobile phone systems must achieve spectral efficiency from a wide bandwidth required to support voice, data and video multimedia applications. These systems generate varying envelope signals and require linear transmitters to preserve the signal integrity and prevent spectrum regrowth. To achieve single chip implementation, the power amplifiers (PAs) in such transmitters must be designed in CMOS which is the technology of choice in realizing the digital baseband processors.;The transmitter front-end prototype presented in this work is designed in a standard 0.18mum CMOS technology. It occupies an area of 5mm2, operates from a 1V supply and provides better than 42dBc adjacent channel power ratio with an output bandwidth of 50MHz at 8GHz. It also provides 22dBm average output power with a power added efficiency of 38% for a 60° outphasing angle.;The PS transmitter front-end is the first fully integrated CMOS wireless implementation to operate at 8GHz from a 1 V supply. It does not require mixers and hence provides an intermodulation distortion free output spectrum, making it a suitable choice for 4G mobile communication systems.;To allow the integration of highly efficient power amplifiers in 4G transmitters, a novel phase shifted (PS) architecture is presented in this work. The PS transmitter achieves a high level of linearity by using outphasing. It adjusts the phase of the two constant envelope RF signals using phase shifters and amplifies these two RF signals using switching class F power amplifiers to achieve a high level of efficiency. The two constant envelope, varying phase RF signals, are finally added together using a wideband combiner to produce an amplified linear replica of the RF signal.
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