In recent years, switching speed of DC-DC converters has increased as the switching frequency has become higher. As a result, high-frequency noise is generated when inductance and stray capacitance of the wiring of board or inside IC resonate due to a sudden change in input current. The high-frequency noise can conduct to external circuits and cause abnormal operation of the set. This Solution Guide introduces examples of noise countermeasures using a three-terminal filter (feed-through filter for power lines) with low ESL, which is effective for noise countermeasures against noise generated on the input side of DC-DC converters.

Automakers are incorporating more multifunctional capabilities into automobiles as they seek to make autonomous driving a reality. Electronic control units (ECUs) for advanced driver assistance systems are consuming more power, and the latest trend is toward ECU integration—installing an ECU close to the engine room or other working part.

If communication waves from cellular or Wi-Fi sources interfere with and intrude into microphone lines for smartphones or other devices, some of their components will become noise components in audible bands known as "TDMA noise", and may be emitted from speakers as unpleasant sound. Countermeasures which implement combinations of TDK's noise suppression filters and ESD Notch Filters can not only demonstrate outstanding effectiveness at suppressing TDMA noise with no effect on signals, but can also provide a variety of other benefits such as improving cellular or Wi-Fi communication reception sensitivity, and providing countermeasures against ESD (electrostatic discharge).

The shunt-through connection is a mounting method in which a component is connected in parallel with the power line, and produces an excellent effect for decoupling of the power line. This article will explain each mounting method and their advantages in detail.

The YFF-AC/AH series 3-terminal feed-through filters offer excellent performance for decoupling of the power lines of automotive electronics.

The radiation noise countermeasure in power lines of in-vehicle electronic equipment provided by TDK's YFF series 3-terminal filters is introduced in the following, based on case examples of evaluation and measurement.

A capacitor is the most basic electronic component for noise suppression in power lines of electronic equipment. A capacitor has a characteristic that, the higher the frequency, the easier the current passes through it, and when a power line is connected to the ground through a capacitor, high-frequency noise is bypassed to the ground and separated.

Ensure voice quality, Prevent degradation of reception sensitivity (self-poisoning), Suppress harmonic distortion in Class-D amplifiers in Noise Suppression Filters for Audio Lines