All-digital RF signal generation for software defined radio

Abstract

Digital generation of radio-frequency signals is a key concept of software defined radios. This paper presents a digital transmitter chain including a very high-speed delta-sigma modulator. It comprises also baseband processing, sample rate conversion, digital upconverter and output stages (switching- mode amplifier and BAW filters). About 74 dB of ACLR (adjacent channel leakage ratio) is obtained on the 7.8 GS/s output of the delta-sigma modulator for the WCDMA standard.