Re: S11 inductance measurement
If a default RLC resonant circuit appears, then click the Circuits menu, and go to Op Amps >> Gyrator.
https://tinyurl.com/yah5tp4t
I wonder why your tinyurl fails?
http://tinyurl.com/y983s4bo
Thanks, Tony. Your tinyurl link works fine. It displays the gyrator circuit.
My link was produced by Falstad's version 1.5n which is no longer up-to-date with the website version. I suspected it would misbehave. I use the older version because it allows me to rearrange scope traces by editing the file directly in the Export window.
I must confess I've never computed L from s11.
From your datasheet. 50 Ohms @ 100MHz has s11 =0.333, 30 degrees which is a VSWR of 2.0 and return loss of 9.6 dB
Z = Zo * ((1 + Γ) / (1 - Γ))
Γ = (Z - Zo) / (Z + Zo)
S11 = 20 * Log10(mag)
Reflected power is the square of reflection coefficient or 1/9th or 11.1% in this example.
same example
Z= 82.9Ω +j30.7Ω
L=Z_Im/2πf
L= 30.7/(2π*1e8Hz) = 49 nH
have fun.
Why do "denominator addition" and "numerator addition" ?
Do you guys have any idea how the author arrived at this expression exactly ?
Surely learn and study very basic things.
Z=(1+S.11)/(1-S.11)
Z_numerator=1+S.11=(1+S.11_re) + j*S.11_im
Z_denominator=1-S.11=(1-S.11_re) + j*(-S.11_im)
Z_numerator_re=1+S.11_re
Z_numerator_im=S.11_im
Z_denominator_re=1-S.11_re
Z_denominator_im=-S.11_im
Could anyone tell me why I am not getting Leq to be 1nH ?
The following is the netlist for the test circuit :
* gnetlist -g spice-noqsi -o test_active_inductor.net test_active_inductor.sch * SPICE file generated by spice-noqsi version 20130710 * Send requests or bug reports to jpd@noqsi.com RZ1 Vtest Ltest 50 Vtest Vtest GND dc 1 +ac 1 .GLOBAL Vdd Vss .PARAM SUPPLY=3.3v .options TEMP=25 .MODEL n1 NMOS .MODEL p1 PMOS .INCLUDE CMOS_Inverter.net .INCLUDE Gm2.net Vd Vdd GND 'SUPPLY' Vs Vss GND 0V Ltest Ltest GND 1n .control set noaskquit AC LIN 1000 100Meg 200Meg run let S11=(2*v(Ltest)/v(Vtest)-1) settype s-param S11 let S11db=db(S11) settype decibel S11db let P11=180*ph(s11)/pi settype phase P11 plot s11db ylimit -0.5 0 plot P11 print S11 > S11.log *plot smithgrid S11 *wrs2p s3046.s2p S write touchstone vers. 1 file s3046.s2p .endc
Found the root cause for the miscalculation.
I forgot to multiply by Zo which is 50ohm
You can still do that with this version
http://tinyurl.com/y946spno
http://tinyurl.com/y72hdnj6 without current trace