RF Circuit Design Techniques for MF-UHF Applications

2	MF-UHF Inductor Design Techniques

2.1  INTRODUCTION

If a current flows through a wire wound, a flux is produced through each turn as a result of magnetic flux density as shown in Figure 2.1. The relation between the flux density and the flux through each turn can be represented as

$\Psi ={\displaystyle \int \overline{B}\cdot d\overline{s}}$

(2.1)

If there are N turns, then we define the flux linkage as

$\lambda =N\Psi =N{\displaystyle \int \overline{B}\cdot d\overline{s}}$

(2.2)

Inductance is defined as the ratio of flux linkage to the current flowing through the windings and defined by

$L=\frac{\lambda }{I}=\frac{N\Psi }{I}$

(2.3)

The inductance defined by Equation 2.3 is also known as self-inductance of the core that is formed by the windings. The core can be an air core or a magnetic core.

FIGURE 2.1 Flux through each turn.

2.2  AIR CORE INDUCTOR DESIGN AND ...