Printed Inductor With Shorting Bars Deletable by Laser for Adjusting the Value of Inductance
Original Publication Date: 1985-Dec-01
Included in the Prior Art Database: 2005-Feb-19
The drawing shows a printed conductor 2 formed in a spiral pattern on a surface 3 of a metallized ceramic chip carrier. At the center of the spiral the conductor terminates in a pad 4 that is connected through the ceramic layer to a return conductor printed on another surface. Shorting bars 5 extend across the turns of the spiral in four radial lines. For most applications, the spiral pattern is made very small and it has an inductance of a few nanohenries in the configuration of the drawing in which none of the shorting bars have been deleted. To achieve a selected value of inductance, shorting bars are deleted in sequence, beginning with the first bar on the outermost turn. When the inductance is close to the desired value, shorting bars may be removed from the innermost part of the spiral for fine adjustment.