News and New Products

Single-chip FM tuner enables embedded broadcast receiver

By Bill Schweber -- EDN, 4/28/2005

What would EH Armstrong say? The FM (and superheterodyne) pioneer never envisioned an all-CMOS, single-IC FM tuner, such as the Si470x series from Silicon Laboratories. This highly integrated, 4×4-mm digital component needs just a bypass capacitor and takes less than 20 mm² of board space overall, far less than the typical approach, which requires a 6×6- mm IC, more than 30 support components, and 150 mm² of space (Picture).

The single-chip tuner, the vendor asserts, is the industry’s first all-CMOS device. It simplifies embedding a conventional broadcast FM receiver, spanning 76 to 108 MHz, into a cell phone or an MP3 player, for example, and thus it is “easy and cost-effective to add FM radio as a standard feature to virtually any application,” according to Ed Healy, vice president at Silicon Labs. And, even if you think broadcast radio is dead, many consumers do not; it is increasingly a feature on portable wireless devices.

The Si4700 version needs no alignment. It includes the required filtering, AGC (automatic gain control), a frequency synthesizer with a VCO (voltage-controlled oscillator), a low-dropout amplifier for direct battery connection, and audio-processing functions. The Si4701 adds an integrated preprocessor for the European RDS (Radio Data System) and the US RBDS (Radio Broadcast Data System) formats at a 57-kHz offset, which adds station ID and song name along with the music and allows alternate-channel (frequency) information, which European radio provide, in which a single broadcaster uses multiple frequencies.

The Si4700 sells for $3 (10,000), and the Si4701 sells for $3.50. The companion evaluation board costs $150.

Silicon Laboratories Inc, www.silabs.com.