Analysis of noise-generation mechanism in a DC-DC converter with a common-source type active-clamp circuit

摘要

An active-clamp circuit is an effective method to suppress the switching surge and to achieve the soft switching operation in switching dc-dc converters. Recently, the common-source type active-clamp circuit has been proposed to connect directly the source terminals of the two MOS-FET switches for simplicity of their driving circuits. Previously, we have reported that this common-source type has a good feature of the common-mode noise reduction. In this paper, the noise-current paths in the DC-DC converter with the common-source type active-clamp circuit are examined in detail by using a small-size magnetic sensor, and the common-mode noise generation mechanism is analyzed by using a high frequency equivalent circuit.