Hi,
I'm trying to specify a frequency dependent resistance (an approximation of the skin effect).
I have a parameters include file, and need to specify the frequency within an expression (in curly brackets) as follows:
S3_skin_tu1 = {PI*PWR(S3_r_tu1-SQRT(2*S3_res_tu1/(2*PI*FREQUENCY*u_Cu)),2)}
However, PSpice does not understand 'FREQUENCY' (nor 'FREQ' or anything else I've tried). I've not been able to find anything in the documentation.
Does anyone know of a way to use AC frequency in an expression?
Any suggestions will be gratefully received!
Regards,
Nick
So to clarify what I do to simulate the skin effect...
in my include file I have the following definitions:
* AC skin effect+ freq = 6900+ ang_freq = {2*PI*freq}+ mu0 = {4*PI*1E-7}+ mur_Cu = 0.999994+ mur_Al = 1.000022+ mu_Cu = {mu0*mur_Cu}+ mu_Al = {mu0*mur_Al}+ skin_Cu = {SQRT(2*res_Cu/(ang_freq*mu_Cu))}+ skin_Al = {SQRT(2*res_Al/(ang_freq*mu_Al))}
giving the AC skin penetration depth for copper and aluminium, which is then used in later expressions.
Typically I'll sweep frequency from 5000Hz to 9000Hz, but the AC skin effect is calculated using the 'freq' parameter (shown above as set to 6900Hz) so the PSpice frequency sweep output will only be accurate close to 6900Hz.
To do an accurate frequency sweep I'd have to do separate runs while manually changing the 'freq' value each time.
It must be within PSpice's ability to have 'freq' set to the actual AC frequency of the simulation!
Anyone know how it can be done? If not, then I request this be added as a feature in a subsequent OrCAD update :)