NGspice Transmission Line Simulation
时间：03-30
整理：3721RD
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Hi,
I am trying to simulate a transmission line in NGspice but it doesn't seem to give me the expected results. I have a 2.3GHz ideal source with a 50 ohm internal resistance connected to one end of the transmission line. At the other end I terminate the transmission line at a 50 ohm load. The characteristic impedance is 50 ohm.
The simulation results give me a match at half wavelength, however, as I start decreasing the wavelength the voltage across the load starts decreasing and when I reach quarter wavelength it gives me Vout=0.
Any ideas? Here is my source code:
I am trying to simulate a transmission line in NGspice but it doesn't seem to give me the expected results. I have a 2.3GHz ideal source with a 50 ohm internal resistance connected to one end of the transmission line. At the other end I terminate the transmission line at a 50 ohm load. The characteristic impedance is 50 ohm.
The simulation results give me a match at half wavelength, however, as I start decreasing the wavelength the voltage across the load starts decreasing and when I reach quarter wavelength it gives me Vout=0.
Any ideas? Here is my source code:
Code:
*.MODEL ymod txl R=0 G=0 L=341.8n C=136.7p length=15.9m *Y1 Vin 0 Vout 0 ymod T1 Vin 0 Vout 0 Z0=50 F=2.3G NL=0.1 Rout Vout 0 50 Rsource Vout Vsource 50 V1 Vsource 0 AC 1 sin(0 1 2.3G) .controltran 1000f 10nplot Vout .endc
Vout is a complex vector.
plot Vout
is
plot real(Vout)
Maybe you want to look at
plot mag(Vout)
Holger
Vout is not a complex vector because it is tran analysis. Indeed, when I do plot real(Vout) or mag(Vout) it gives me the same results. Anyway, the weired thing is I get a decaying sine wave at Vout.
I think you should have both 50 ohm source and load impedance.
I have 50 ohm source, load and characteristic impedance.
No, you don't. I guess you meaned to write. Now you have a mismatched and unterminated transmission line.
Code:
Rsource Vin Vsource 50
I feel stupid now. Thanks.
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