Analysis of design specification for digital polar RF transmitter at system and architectural level

The polar transmitter is an alternative RF transmitter architecture solution for highly efficient amplification of nonconstant envelope signals. This paper presents an analysis of system performance of digital polar RF transmitters. The approach is to analyse the relation between error vector magnitude (EVM) and output power spectrum density (PSD). The requirements on amplitude dynamic range, bit resolution and time delay mismatch for AM/PM paths are studied and used to specify the design of digital polar RF transmitters. All the components in the digital polar RF transmitter have been modelled both in Matlab and SystemC. The analysis and simulation can be completed within seconds. Based upon the presented analysis results, optimum design parameters for the components and system can be easily derived. With the analysed specification, the performance of the polar transmitter regarding EVM and PSD is verified at the system level as well.