Fabrication of Transmission-Line Transformer Using a Fine-grain Mn-Zn Ferrite

Abstract

A novel high-frequency transformer using a fine-grain Mn-Zn ferrite has been proposed for transmission line use. The device consists of a fine-grain Mn-Zn ferrite core, polyimide film, copper planar spiral winding, and copper ground-plane, which operate as a distributed constant circuit. A quarter-wavelength transmission-line transformer with a large voltage-gain under higher impedance termination has been investigated, and it has been applied to a step-up transformer in a high-frequency inverter for a cold fluorescent lamp (CFL).