New DFE Spans 100MHzSeptember 19, 2012
Author: Joseph Byrne
Broadcom is sampling its newest digital front end (DFE) for base-station radios, the BCM51030. Due to enter production in December, its most significant new feature is support for bands up to 100MHz wide, enabling a single chip to process multiple smaller channels (e.g., 5MHz or 20MHz) and funnel them to a single antenna. Alternative DFE solutions are limited to 10MHz, and each 10MHz or smaller channel requires the additional expense of its own antenna.
The BCM51030 also simultaneously supports two or four antennas, such as for MIMO radios. For higher-order MIMO or beam forming, multiple BCM51030 chips can work in parallel, synchronizing their processing. To further reduce cost, the chip integrates digital down- and up-conversion. Another added feature is support for the new JESD204 interface standard for connecting A/D converters. Conspicuously absent, however, is a CPRI interface.
Broadcom obtained the DFE product line when earlier this year it acquired NetLogic, which bought DFE-startup Optichron in 2011. The primary alternatives to a DFE ASSP are in-house designs implemented in FPGAs or ASICs. Broadcom claims its primary advantage is its proprietary predistortion algorithm, which enables support for wide (e.g., 100MHz) bands, reduces power dissipation, and improves system reliability. Moreover, its flexibility allows a single chip to work in different systems, each supporting different protocols and frequency bands, reducing design time and cost.