ST shrinks next-gen Bluetooth designs by connecting antenna through a single chip

GENEVA, SWITZERLAND: Two new ICs from STMicroelectronics allow designers to connect an antenna to a Bluetooth transceiver using a single chip, making Bluetooth-enabled products simpler, smaller and easier to build.

The BAL-2593D5U and BAL-2690D3U are integrated baluns, used to convert the antenna signal to a balanced pair of signals as required by the Bluetooth transceiver.

As replacements for traditional baluns built with discrete components, the new devices occupy up to 70 percent less printed-circuit-board area, simplify design and assembly, and ensure better balanced signal channels with low losses, thereby improving wireless performance.

The ICs comprise Integrated Passive Devices fabricated using ST's proven IPD-on-glass process, which delivers more predictable RF performance compared to other integrated baluns; some of which require additional external matching components.

The BAL-2593D5U is optimized for use with the STLC2500D standalone Bluetooth transceiver and STLC2592/3 combo devices, which implement an FM radio tuner enabling users to listen to radio directly on a Bluetooth headset. The BAL-2690D3U is designed to partner the STLC2690, a Bluetooth/FM-tuner combo that also adds a short-range FM transmitter allowing the user to play stored music through a system such as a car radio.

Key features of ST's integrated baluns:

BAL-2593D5U:
50/50+j50 Ohm impedance
1.16 x 1.26mm footprint; sub-0.7mm profile
1.2dB insertion loss
Matches STLC2592/3, STLC2500D

BAL-2690D3U:
50/30+j25 Ohm impedance
0.91 x 0.91mm footprint; sub-0.7mm profile
0.8dB insertion loss
Matches STLC2690

The BAL-2593D5U and BAL-2690D3U are in production now, in 4-bump flip-chip packages, priced at $0.25 for a minimum order of 5,000 pieces; additional pricing options are available for higher quantities.