Mixerless Transmitters for Wireless Communications

Abstract

There is immense research in developing digital transmitters that are multi-standard and reconfigurable. A promising technique is RF Digital to Analog Converter (RFDAC), where the input digital baseband signal is directly converted to an analog RF signal. The existing RFDAC based transmitters use mixers and adopt filtering to avoid mixer spurs. Polar transmitters too use mixers and need filtering. The use of RF filtering in these transmitter topologies limits the bandwidth and therefore the multi-standard reconfigurability of such transmitters. This thesis aims to develop mixerless transmitter architectures that are reconfigurable. A mixerless polar modulator-based transmitter and a mixerless three-way amplitude modulation based transmitter are proposed for OFDM signals. The proposed architectures translate the baseband signal to RF without using mixers. The topologies do not have any emissions over a wide frequency band. The large RF bandwidth and the absence of filters make the designs more reconfigurable and suitable for integration.