This thesis is composed of nine publications and an overview of the research topic, which also summarises the work. The research described in this thesis focuses on research into the digitalisation of wireless communication base station transmitters. In particular it has three foci: digital modulation, D/A conversion and switching-mode power amplification. The main interest in the implementation of these circuits is in CMOS.The work summarizes the designs of several circuit blocks of a wireless transmitter base station. In the baseband stage, a multicarrier digital modulator that combines multiple modulated signals at different carrier frequencies digitally at baseband, and a multimode digital modulator that can be operated for three different communications standards, are implemented as integrated circuits. The digital modulators include digital power ramping and power level control units for transmission bursts. The upconversion of the baseband signal is implemented using an integrated digital quadrature modulator.The work presented provides insight into the digital-to-analogue interface in the transmitters. This interface is studied both by implementing an intermediate frequency D/A converter in BiCMOS technology and bandpass Delta-Sigma modulator-based D/A conversion in CMOS technology.Finally, the last part of the work discusses switching-mode power amplifiers which are experimented with both as discrete and integrated implementations in conjunction with 1-bit Delta-Sigma modulation and pulse-width modulation as input signal generation methods.
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