Agilent Wide Range DC Current

Introduction
A large number of switching power supply inductors with extended high frequency
characteristics have recently been developed. The reason for this is the increase in the
switching frequency to reduce size of switching power supplies which are being built
using electronic components which are more compact than are conventional compo-
nents. However, if components which are not suitable for high frequency are used,
the increase in the frequency lowers the efficiency of the switching power supply and
creates electrical noise. Consequently, lower noise components and circuits for use at
higher frequencies must be developed for future switching power supply designs.
Inductors are one of the easiest components to reduce in size by raising the frequency
and will require the development of low-loss, low leakage cores. The development and
production of such inductors requires DC current biased inductance measurements to
evaluate the inductance characteristics under actual operating conditions.
This application note describes DC current biased inductance measurements that are
more accurate and made over a wider frequency range than was previously possible.