On the Concept of a Multi-Mode Agile Receive Digital-Front-End for Cellular Terminals

Inhalt:
This paper describes the concept of a highly reconfigurable digital-front-end (DFE) enabling multi-mode capable RF receivers for cellular applications, based on the well known direct conversion receiver (DCR) architecture. Its main functionality includes sample-rate-conversion, channel selection filtering, dynamic range control, imbalance correction and matched filtering. The described partitioning shifts some of the functionality, normally located in the analog-front-end (channel filtering, gain control) or the baseband IC (matched filter) to the digital-frontend. The DFE concept allows shifting all analog and mixed-signal blocks to the RF IC, whereas the baseband processing is left purely digital and thus can make use of main stream technology such as CMOS. The technology shift towards RF-CMOS further favors this strongly digital receiver architecture.