Choke coils reduce radiation noise in electronics

Murata's high-precision film inductor forming technology was mobilised to successfully attain an improved cut-off frequency in the transmission characteristics of these choke coils compared with previous products.

In the DLP11TB series, Murata has successfully boosted the cut-off frequency of the common mode choke coils to 8GHz or more, enabling USB3.0 Super Speed signals to be transmitted at more than satisfactory quality.

The recent debut of SSDs (solid state disks) and other high-speed peripheral devices has led to the formulation of the USB 3.0 standard, under which the data-transmission speed is increased from the 480Mbps provided by USB 2.0.

USB 3.0 has added the Super Speed mode, enabling data to be transmitted at up to 5Gbps, representing a tenfold increase over the speed provided by the previous standard.

With the increased data transmission speed provided by USB3.0, the signal frequencies have become much higher than with USB 2.0.

It is therefore difficult to deal with noise issues while maintaining a satisfactory signal quality using an ordinary common mode choke coil.

The DLP11TB series' 1.25 x 1.0mm size makes it optimally suited to mobile devices.

The devices' cut off frequency has been boosted to more than 8GHz to reduce the effects of noise on signals to the absolute minimum.

Features include a high common mode impedance of 80Ohms at 100MHz and the coils match the characteristic impedance of 90Ohms from the USB 3.0 standard.

Noise outflow due to mode conversation is minimal.