A high-integration difference of opinion
-- EDN, January 20, 2000
Broadcom' BCM7020 chip (Picture) represents its response to ATI's (www.atitech.com) Rage standard-definition-TV (SDTV) and high-definition-TV (HDTV) graphics controllers (see "3-D graphics branch out to set-top boxes," EDN, Jan 6, 2000, pg 30). Both companies announced the chips at December's Western Cable show, and both chips target set-top boxes but from different perspectives. A comparison of their features clarifies these disparities.
ATI is first and foremost a graphics company with a notable additional amount of video expertise. So, you'd expect Rage SDTV and HDTV to offer comparatively robust 3-D-graphics features, and you'd be right. On the other hand, Broadcom's chip can simultaneously decode multiple incoming video streams (for picture-in-picture or multiple-camera-angle applications). The BCM7020 also hardware-decodes and mixes incoming MPEG, Dolby Digital, and PCM audio streams versus relying on a separate audio-decoder chip or host CPU-based software decoding as the ATI approach would require.
Both ATI and Broadcom's devices adopt a unified-memory architecture. However, ATI provides two versions of its digital-TV chip set, whereas Broadcom relies on one device with varying required amounts of system memory to support both SDTV- and HDTV-targeted systems. The BCM7020, in many respects a single-chip integration of Broadcom's BCM-7010 set-top-box decoder and BCM7014 advanced-TV-graphics system, also includes a composite analog video decoder with a 10-bit A/D converter. Now available for sampling, the BCM7020 costs $50 (10,000) and comes in a 420-bump TBGA package.
Broadcom Corp, 1-949-450-8700, www.broadcom.com.
—by Brian Dipert
