# SPICE's Fourier transform

Discussion in 'Homework Help' started by interesting_dude, Dec 1, 2013.

1. ### interesting_dude Thread Starter New Member

Jul 28, 2013
20
0
Hello everybody!
What am I doing wrong in attempts to simulate an example circuits with FFT? Why do my results not correspond to these ones in the book? With earlier simulations everything matched excellently!
Huge thanks for any decent explanations!

******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
**** FULLWAVE BRIDGE RECTIFIER
**** INPUT LISTING TEMPERATURE = 27.000 DEG C
***********************************************************************

V1 1 0 SIN(0 15 60 0 0)
RLOAD 2 3 10K
D1 1 2 MOD1
D2 0 2 MOD1
D3 3 1 MOD1
D4 3 0 MOD1
.MODEL MOD1 D
.TRAN .5M 17M
.PLOT TRAN V(1,0) V(2,3)
.FOUR 60 V(2,3)
.END

******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
**** FULLWAVE BRIDGE RECTIFIER
**** DIODE MODEL PARAMETERS TEMPERATURE = 27.000 DEG C
***********************************************************************

MOD1
IS 1.00E-14

******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
**** FULLWAVE BRIDGE RECTIFIER
**** INITIAL TRANSIENT SOLUTION TEMPERATURE = 27.000 DEG C
***********************************************************************

NODE VOLTAGE NODE VOLTAGE NODE VOLTAGE

( 1) 0.0000 ( 2) 0.0000 ( 3) 0.0000

VOLTAGE SOURCE CURRENTS

NAME CURRENT

V1 2.789E-40

TOTAL POWER DISSIPATION: 0.00E+00 WATTS

******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
**** FULLWAVE BRIDGE RECTIFIER
**** OPERATING POINT INFORMATION TEMPERATURE = 27.000 DEG C
***********************************************************************

**** DIODES

D1 D2 D3 D4
MODEL MOD1 MOD1 MOD1 MOD1
ID 4.35E-21 4.35E-21 4.35E-21 4.35E-21
VD 0.000 0.000 0.000 0.000

******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
**** FULLWAVE BRIDGE RECTIFIER
**** TRANSIENT ANALYSIS TEMPERATURE = 27.000 DEG C
***********************************************************************

LEGEND:

*: V(1)
+: V(2,3)
TIME V(1)
*)------------- -2.000E+01 -1.000E+01 0.000E+00 1.000E+01 2.000E+01
- - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+)------------- 0.000E+00 5.000E+00 1.000E+01 1.500E+01 2.000E+01
- - - - - - - - - - - - - - - - - - - - - - - - - - - - -
0.000E+00 0.000E+00 + . * . .
5.000E-04 2.807E+00 . + . . * . .
1.000E-03 5.512E+00 . + . . * . .
1.500E-03 8.029E+00 . . + . * . .
2.000E-03 1.025E+01 . . + . * .
2.500E-03 1.213E+01 . . . + . * .
3.000E-03 1.354E+01 . . . + . * .
3.500E-03 1.453E+01 . . . + . * .
4.000E-03 1.494E+01 . . . + . * .
4.500E-03 1.488E+01 . . . + . * .
5.000E-03 1.424E+01 . . . + . * .
5.500E-03 1.313E+01 . . . + . * .
6.000E-03 1.154E+01 . . .+ . * .
6.500E-03 9.550E+00 . . + . *. .
7.000E-03 7.214E+00 . . + . * . .
7.500E-03 4.628E+00 . + . . * . .
8.000E-03 1.878E+00 . + . . * . .
8.500E-03 -9.415E-01 + . *. . .
9.000E-03 -3.723E+00 . + . * . . .
9.500E-03 -6.378E+00 . + * . . .
1.000E-02 -8.803E+00 . . * + . . .
1.050E-02 -1.092E+01 . *. +. . .
1.100E-02 -1.265E+01 . * . . + . .
1.150E-02 -1.392E+01 . * . . + . .
1.200E-02 -1.472E+01 . * . . + . .
1.250E-02 -1.497E+01 . * . . + . .
1.300E-02 -1.473E+01 . * . . + . .
1.350E-02 -1.392E+01 . * . . + . .
1.400E-02 -1.266E+01 . * . . + . .
1.450E-02 -1.091E+01 . *. +. . .
1.500E-02 -8.814E+00 . . * + . . .
1.550E-02 -6.374E+00 . + * . . .
1.600E-02 -3.727E+00 . + . * . . .
1.650E-02 -9.404E-01 .+ . *. . .
1.700E-02 1.880E+00 . + . . * . .
- - - - - - - - - - - - - - - - - - - - - - - - - - - - -

******* 01/12/11 ******** SPICE 2G.6 15/3/83 ******** 14:30:07 ****
**** FULLWAVE BRIDGE RECTIFIER
**** FOURIER ANALYSIS TEMPERATURE = 27.000 DEG C
***********************************************************************

FOURIER COMPONENTS OF TRANSIENT RESPONSE V(2,3)

DC COMPONENT = 8.294E+00

HARMONIC FREQUENCY FOURIER NORMALIZED PHASE NORMALIZED
NO (HZ) COMPONENT COMPONENT (DEG) PHASE (DEG)

1 6.000E+01 4.134E-03 1.000000 109.967 0.000
2 1.200E+02 6.213E+00 1503.001102 -75.620 -185.588
3 1.800E+02 4.711E-03 1.139608 137.077 27.109
4 2.400E+02 1.159E+00 280.425460 -61.412 -171.380
5 3.000E+02 5.575E-03 1.348548 158.142 48.174
6 3.600E+02 4.459E-01 107.855080 -47.527 -157.494
7 4.200E+02 7.568E-03 1.830629 -168.855 -278.822
8 4.800E+02 2.147E-01 51.928957 -34.592 -144.560
9 5.400E+02 7.739E-03 1.872056 -165.930 -275.898

TOTAL HARMONIC DISTORTION = ************ PERCENT

JOB CONCLUDED

TOTAL JOB TIME 0.00

2. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,066
I havent used 2G6 in forty years. Your TRAN statement looks suspicous. You need to run the sim for several whole cycles of the stimulus. The period of 60Hz is 16.667ms. Try running your sim for six cycles (0.1s)

3. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,066
Heres what (free) LTSpice shows: (I made no effort to match your node numbers)

File size:
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4. ### interesting_dude Thread Starter New Member

Jul 28, 2013
20
0
Uh...
I've changed ".TRAN .5M 17M" into ".TRAN .5M .1"  result didn't match completely too. Seems like LTSpice showed "almost" correct results too!
But I think that I've really understood the general idea of that curious chapter in e-book.
Thanks for attention!

5. ### ninjaman Member

May 18, 2013
306
1
what type of circuit is that in the ltspice program please?

I have to show the fundamental, third and fifth harmonics and the fifth has to have a lag of 70 degrees. I wanted to know how I could do this and that circuit may be of use. whats it called so I can look it up. it looks like a rectifier.

thanks
simon

6. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,066
It is a full-wave diode bridge rectifier, drawn differently than you are used to seeing it.

Here a simple way to sythesize waveforms...

The second diagram shows how to set up the voltage sources...

File size:
190.2 KB
Views:
78
File size:
97.2 KB
Views:
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7. ### interesting_dude Thread Starter New Member

Jul 28, 2013
20
0
@ninjaman
http://www.allaboutcircuits.com/vol_2/chpt_7/3.html

I think I found mistake. That netlist should be such:

fullwave bridge rectifier
v1 1 0 sin(0 15 60 0 0)
rload 2 3 10k
d1 1 2 mod1
d2 0 2 mod1
d3 3 1 mod1
d4 3 0 mod1
.model mod1 d
.tran .5m 50m
.plot tran v(1,0) v(2,3)
.four 60 v(2,3)
.end