Ngu Kek Siang
Newbie level 3
Currently I am trying to simulate the noise figure, S11 and S22 parameters for LNA at 2.4GHz in HSPICE. Below is the code I used:
Calculate noise figure:
.ac dec 50 400MEG 3g
.NOISE v(vout) vin 1
Calculate S11 and S22:
.net v(vout) vin rin=50 rout=50
.print s11(db) s11(m) s11(p)
.print s22(db) s22(m) s22(p)
However, I get negative NF after calculate from the following:
**** resistor squared noise voltages (sq v/hz)
element 0:r3
rs 9.1186f
1/f 0.
total 9.1186f
rx 5.2622k
...
**** total output noise voltage = 433.9253f sq v/hz
NF = 10log(9.1186f/433.9253f) = -16.77dB
and get 0 value for S11 and S22:
freq s11 s11 s11
db mag phase
400.00000x 0. 1.0000 180.0000
418.85142x 0. 1.0000 180.0000
...
2.41024g 0. 1.0000 180.0000
freq s22 s22 s22
db mag phase
400.00000x 0. 1.0000 180.0000
...
2.41024g 0. 1.0000 180.0000
Can I know did I do wrongly? Or why these values appear?
Thank you.
Calculate noise figure:
.ac dec 50 400MEG 3g
.NOISE v(vout) vin 1
Calculate S11 and S22:
.net v(vout) vin rin=50 rout=50
.print s11(db) s11(m) s11(p)
.print s22(db) s22(m) s22(p)
However, I get negative NF after calculate from the following:
**** resistor squared noise voltages (sq v/hz)
element 0:r3
rs 9.1186f
1/f 0.
total 9.1186f
rx 5.2622k
...
**** total output noise voltage = 433.9253f sq v/hz
NF = 10log(9.1186f/433.9253f) = -16.77dB
and get 0 value for S11 and S22:
freq s11 s11 s11
db mag phase
400.00000x 0. 1.0000 180.0000
418.85142x 0. 1.0000 180.0000
...
2.41024g 0. 1.0000 180.0000
freq s22 s22 s22
db mag phase
400.00000x 0. 1.0000 180.0000
...
2.41024g 0. 1.0000 180.0000
Can I know did I do wrongly? Or why these values appear?
Thank you.