Combined Dual ESD/EMI Audio Filter

September 24, 2009

With ten discrete component functions integrated on one chip, the new EPCOS ESD/EMI audio filter enables high audio quality in stereo headsets, mobile phones, portable multimedia players, PDAs and notebook computers.

EMI can be generated by RF transmissions and affect audio lines. At the same time, audio inputs or outputs can cause distortion on RF lines. The new combined dual ESD/EMI audio filter (CA04F2FT5AAUD010G) effectively reduces parasitic noise and increases audio quality. The filter features low series resistance and combines EMI filtering and ESD production in a 405, 2-fold array package.

With a cut-off frequency of 20 MHz and low serial resistance of 0.2 Ω, this component is an excellent solution for applications requiring low bandpass attenuation. At frequencies from 200 MHz to 4 GHZ, the attenuation is higher that -20 dB for all quad-band GSM (850/890/1800 MHz) and UMTS standards (2.1 GHz), as well as for GPRS/WLAN and Bluetooth (2.4 GHZ). At 900 MHz, it offers very high attenuation of more than -60 dB.

Traditional filters that employ TVS and Zener diodes in the audio signal path possess highly nonlinear characteristics and, therefore, can seriously increase total harmonic distortion (THD). By contrast, the EPCOS dual ESK/EMI audio filter features a low THD and noise value less than -100 dB at 1 kHz.

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The design of the EPCOS ESD/EMI audio filter also enables excellent ESD protection for sensitive ICs (IEC 61000-4-2, level 4 standards). Its internal structure provides a double-clamping function and is therefore able to reduce the ESD pulses from 8 kV to 70 V. Moreover, the ESD/EMI audio filter features a highly stable ceramic structure. Even after ± 1000 ESD pulses, the dual ESD/EMI audio filter continues to deliver the same high filtering performance.