[SOLVED] Target Impedance and Trace width Relation

[mishrashashi]

Dear All,

For a power trace, does target impedance matching require? I know Target Impedance formula :
Ztarget=(Power Supply Voltage X Allowed Ripple)/Current
ex: Ztarget(3.3V)=(3.3Vx5%)/2A=82.5mOhm

On the basis of this formula how a designer can deside the width of the trace? Does any relationship between Ztarget and tracewidth?
I know Z target is different from Z0 (char. Impedance) and tracewidth calculation with Z0. But Ztarget and tracewidth relation..... :???: ?

 

[loosemoose]

if you are talking about power traces providing current to IC's, then you want the lowest impedance possible.

 

[mishrashashi]

Hi Loosemoose,
I'm talking about power traces only. I want to know that how to maintain lowest target impedancce with trace. Does it depend on trace width, height or length? I want to know relation(equation) between these parameters.

 

[loosemoose]

the impedance depends on the geometry of the actual trace, but not the length. width, thickness and height above ground. the impedance will also change if there are other traces nearby.
just Google " impedance calculator" for formulas.