Innovative protected common mode filters support high speed serial interfaces

May 24, 2011 // By Paul Buckley
ON Semiconductor has introduced a new range of common mode filter (CMF) devices with integrated electrostatic discharge (ESD) protection to suppress noise and provide strong signal integrity. The new EMI2121, EMI4182 and EMI4183 devices are suitable for implementation in smartphones, media tablets, wireless connectivity dongles and digital camcorders, as well as set top boxes and DVD players.

Unlike traditional electromagnetic interference (EMI) filters, the new CMFs from ON Semiconductor are realized in silicon making them better suited to suppress EMI to deeper levels and at higher frequencies than ceramics or ferrite based solutions. Integrating ESD protection with EMI suppression offers space savings of up to 50 percent compared to competitive solutions, translates into significant bill-of-materials (BOM) savings and is a turnkey solution for wireless handset designers.     

The EMI2121 single pair CMF, EMI4182 dual pair CMF and EMI4183 triple pair CMF all offer a common mode rejection of 15 dB (typical) at 500 MHz and an insertion loss of only 1.0 dB (typical) at 500 MHz. Their high differential mode bandwidth cutoff frequency ensures high levels of signal integrity. The devices feature integrated ESD protection that meets a peak discharge of 15 kV per the IEC61000-4-2 standard. They support an operating temperature range of −40 to +85 ⁰C, and each have a clamping voltage of 32 V, which typically is at least thirty times better than existing ceramic solutions.     

The new devices are optimized for protecting high speed differential ports using the MobileIndustry Processor Interface(MIPI) DSI, and MIPI CSI2 interface standards, as well as USB 2.0 - the current versions of High-Definition Multimedia Interface (HDMI). The protected CMF family of products supports data speeds of up to 3.4 Gbps, well above what is required for the MIPI, USB 2.0, and HDMI interfaces, while providing high levels of signal integrity.

The EMI2121 is offered in a 2.2 mm x 2.0 mm x 0.75 mm QDFN8 package and is priced at $0.19 per unit in 10,000 unit quantities. The EMI4182 is offered in a 2.5 mm x 2.0 mm x 0.75 mm 10 pin WDFN package and is priced at $0.25 per unit in 10,000 unit quantities and the EMI4183 is offered in a 4.0 mm x 2.0 mm x 0.75 mm 16 pin WDFN package and priced