EMI Suppression Filters (EMC and Noise Suppression)Overview of Course for Noise Suppression against LTE Noise

Lately, a need for high data transmission rate is on the increase with the trend of large-capacity wireless communication services. The Long Term Evolution (LTE) that is to be used by mobile carriers around the world meets this need as a wireless communication standard. The data communication rate of this communication system is higher than that of 3G/3.5G (such as W-CDMA) with low delay. With its superior radio wave use efficiency, this communication system is expected to spread rapidly. However, if noise of an LTE compatible terminal interferes with the wireless communication band, communication quality in throughput or receiving sensitivity will be degraded. To solve this problem, noise suppression technology (intra-system EMC) is important.

Several factors that degrade communication quality exist in recent mobile terminals due to increase in frequency of data signals (including MIPI) and composite digital circuits. In particular, a phenomenon of degradation in LTE communication quality caused by the interference of noise from a terminal with its antenna becomes a problem. To solve these problems, electromagnetic noise must be observed accurately. Specifically the following items must be carried out.

According to the noise level examined in the previous section, select the best parts for noise suppression and insert them into noise paths to reduce noise that enters wireless circuits to improve the communication quality. This section introduces examples of noise suppression for an actual LTE-compatible terminal (Band13: 700 MHz band, Band4: 2G Hz band) .

Noise on the LCD data line and the power line interfered with the antenna and entered reception wireless waves, which degraded the communication quality. A successful example of noise suppression implemented to improve the communication quality is introduced below.

The harmonic component in the camera's clock signal interfered with the antenna and noise entered reception wireless waves, which degraded the communication quality. A successful example of noise suppression implemented to improve the communication quality is introduced below.

This section introduces how to select basic EMI filters. In addition, this section describes selection points of noise suppression parts introduced in the 3rd period "Examples of Noise Suppression against LTE Noise."