Handset audio filter is first to battle ESD

Tiny device provides dual functionality to improve sound quality in cell phones

The EMIF06-AUD01F2 handset audio filter integrates capacitors and TVS diodes in a 2.42 x 1.92-mm flip-chip package, and claims to be the first circuit-protection device to offer complete EMI filtering and ESD protection for handset speaker and microphone channels in portable audio applications. Reducing board-space requirements by more than 50% compared to previous integrated solutions using two ICs with external resistors and up to 77% compared to discrete solutions, the device also combines all necessary biasing circuitry as well as a 10-Ω series resistor in the speaker output.

The high-density 1.3-nF PZT capacitors on the microphone lines eliminate audible handset demodulation noise by achieving –25-dB attenuation over the 800 to 2,480-MHz bandwidth, while the integrated TVS diodes, low-inductance packaging, and a Z-R-Z pi-filter topology protect against ESD. The TVS diodes have a 20-V peak clamping voltage, enabling the device to meet IEC61000-4-2 level 4 ESD protection at the external pins.

Total harmonic distortion is less than –75 dB, and the device achieves audio-power transfer by delivering 135 mA per speaker channel. ($0.55 1,000—available now.)

STMicroelectronics , Lexington , MA
Information 781-861-2650
http://www.st.com