A Multi-Mode Capable Receive Digital-Front-End for Cellular Terminal RFICs

Developments aimed at the software-defined-radio (SDR) concept for cellular applications received increasing attention due to the necessity of multi-mode/multi-system capable terminals for next generation cellular communication systems. This paper describes a highly reconfigurable digital-front-end (DFE) enabling multi-mode capable RF receivers for cellular applications. Its main functionality includes sample-rate-conversion (SRC), channel filtering, dynamic range control, and signal conditioning for transmission via a digital interface between RFIC and baseband IC. The described partitioning shifts some of the functionality, normally located in the analog-front-end (channel filtering, gain control) and the baseband IC (matched filtering) to the digital-front-end. A receiver IC implementing the proposed concept has been fabricated in 0.13 µm RF-CMOS. The overall measurements have shown a EVM of 3.9 % for UMTS and 3.1 % for IS-95.