Electronic Design

Parallel-Port Filter Extends EMI Protection

Rising clock frequencies and new sources of RF emissions such as WLAN 802.11 are pushing the demand for electromagnetic-interference (EMI) filtering on IEEE 1284 parallel ports. The PACZIG1284, an integrated filter from California Micro Devices, addresses these concerns by providing approximately 30 dB of EMI rejection out to 3 GHz. The part also attenuates frequencies down to 100 MHz.

The PACZIG1284 is comparable to the company's PACSZ1284, which attenuates signals up to 1.5 GHz. Both the PACSZ1284 and the PACZIG1284 integrate the termination resistors and electrostatic-discharge (ESD) protection needed for complete parallel-port protection. Yet the new filter component is constructed using a Zero Inductance Ground technology.

"ZIG" eliminates the wirebond that previously connected the ground on the filter's silicon substrate to the pc board. In the PACZIG1284, the substrate connects to the pc board through an exposed metal pad. According to the company, eliminating the wirebond lowers the inductance in the ground path from about 1 to 1.5 nH to a value that's not measurable.

Housed in a 28-pin QSOP, the PACZIG1284 costs $0.71 each in quantities of 10,000.

California Micro Devices, www.calmicro.com; Joe Salvador, (408) 934-3114.

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