microstrip line inductance decreasing

[yefj]

Hello, If we have a complex long and curved trace and we get problematic insertion loss.
Is the thickness of the trace place a role in the inductance of transmition line?
by the formula bellow its not
And in general what is the general method of improving insertion loss in microstrip trace?
Thanks.

 

[vfone]

Thickness of the trace may not have much influence on the microstrip inductance, but impedance of the trace and its consistency during entire length may play an important role when is about insertion loss.
You mentioned you have a curved trace. A curved trace has minimum parasitic inductance and capacitance (so minimum insertion loss) only when the curving radius is larger than twice of the width of the line.

 

[yefj]

So assume i have a proble with insertion loss in such trace ,how i fix it?
Thanks.

 

[FvM]

Your emphasis on inductance and inductance reduction seems inappropriate. The first point for transmission performance is designing it with matched impedance and keeping the impedance constant along the line. Secondly you have dielectric und resistive losses according to the transmission line geometry and material properties.

It would be helpful to understand what your transmission application and exact design problem is.

 

[yefj]

Hello FVM,i am trying to learn this issue.
Suppose you did simulation and design but in manufatoring it resulted not as you simulated.
How you fix it?
Thanks.

 

[FvM]

Transmission line impedance can vary due to 1. substrate permittivity variation, 2. substrate thickness variation, 3. etching process variations.

The usual way is to adjust the photo mask line width or the etching process according to impedance measurements. (impedance controlled manufacturing).

 

[volker@muehlhaus]

Insertion loss is influenced by metal loss and dielectric loss. If you have a lossy substrate like FR4, substrate losses (loss tangent) have a large effect on line insertion loss.