Noise Countermeasure using 3-Terminal Capacitors with Through Connection

1. Introduction

Noise-control techniques are becoming increasingly important due to high-speed operation of ICs and electrification of automobiles.

This application note introduces examples of using the 3-terminal capacitor as a filter (feedthrough connection) for radiated emission and conducted immunity.

2. Radiated Emission

In the recent years, the switching frequency of DC/DC converters has increased due to the demand for miniaturization of circuits, and their harmonic noise tend to exist up to high frequencies.

In addition, the resonance due to parasitic inductance and floating capacitance of IC and PCB generates high-level noise at high frequency.

As a countermeasure, this note introduces examples in which the 3-terminal capacitor is used at output line or input line of a DC/ DC converter.

The 3-terminal capacitor (Through connection) at DC/DC converter Outputline. (for consumer)

We compared noise reduction effect of a standard 2-terminal MLCC and a 3-terminal low-ESL capacitor.