Concept Engineering of a Reconfigurable, Broadband, and High Performance Modulator for Celluar Basestations

This paper deals with concept considerations for a direct conversion transmitter chip, which is designed in a 0.35 µm SiGe BiCMOS process. The quadrature modulator covers an extremely broad RF bandwidth of 400MHz up to 2.7GHz and should be able to handle different standards like UMTS and GSM. Baseband filtering specifications are covered as well as some key items of the specification list and their derivation from the different standards. Furthermore the used prescaler and the VCO requirements, i.e. the frequency tuning range, are described. Relevant issues are also the consequences of the required RF-frontend reconfi- guration.