Bandwidth considerations for a CALLUM transmitter architecture

This article presents an investigation of the combined analog locked loop universal modulator (CALLUM) linear transmitter architecture. A simple approximate formula is derived, linking the instantaneous frequency of the CALLUM signals to the modulation depth of the information signal. Furthermore, the effect of the frequency mismatch between the VCOs present in the CALLUM architecture is examined, and the need for frequency synchronization via a phase locked loop is discussed.