Filter cleans up handheld displays

A new EMI filter for LCD driver lines will be used in mobile, computing and consumer applications that are subject to increasing interference from wireless applications.

STMicroelectronics has developed an EMI filter for LCD driver lines.

It will be used in mobile, computing and consumer applications that are subject to increasing interference from wireless applications such as cellphones and Bluetooth connections.

The EMIF10-LCD01F1 is a 10-line filter designed to replace capacitor and resistor networks, and to reject rerouted and retransmitted radiation frequencies on the lines between a graphics controller and an LCD.

The part also offers protection against damage from electrostatic discharges (ESD) of up to 15kV.

The part is based on a lowpass RC pi filter, repeated 10 times on silicon and with integrated Zener diodes at each input and output for ESD protection.

The EMIF10-LCD01F1 is rated to meet IEC61000-4-2 standard level 4 ESD requirements.

The filter is offered in a flip-chip package of the same size as the die, reducing board space and also the parasitic inductance in the leads of the device.

This helps deliver superior filtering performance across a wide frequency range, from 900MHz to 3GHz, which makes it suitable for use in dual- to quad-band cellphones.

The EMIF10-LCD01F1 offers 30dB of attenuation at GSM and Bluetooth frequencies.

The EMIF10-LCD01F1 has been designed with line capacitances that support up 30MHz frequencies, to avoid disturbing video signals.

This means the part has little impact on the rise and fall times of video signals and imposes almost no delay.

The part is available in a 6.9mm2 flip-chip package in normal and lead-free versions and is priced at US $0.70 in quantities of 100,000 pieces.

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