MOS operational amplifier
Transient step response of a 27-transistor MOS amplifier.
A 27-transistor MOS operational amplifier (level 2 MOSFETs), driven by a 5V pulse. The transient shows the internal node 20 and the output, node 66, driving a 70pF load.
- v(20)
- v(66)
Output
mosamp2 - mos amplifier - transient
Transient Analysis Tue Sep 29 08:47:02 2026
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Index time v(20) v(66)
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0 0.000000e+00 4.197163e-02 4.197162e-02
1 1.000000e-11 4.336449e-02 4.197207e-02
2 2.000000e-11 4.335072e-02 4.197252e-02
3 4.000000e-11 4.332355e-02 4.197340e-02
4 8.000000e-11 4.327141e-02 4.197512e-02
5 1.600000e-10 4.317527e-02 4.197835e-02
6 3.200000e-10 4.301158e-02 4.198412e-02
7 6.400000e-10 4.277276e-02 4.199349e-02
8 1.000000e-09 4.260490e-02 4.200156e-02
9 1.064000e-09 1.468762e-01 4.221809e-02
10 1.192000e-09 3.382068e-01 4.304200e-02
11 1.330203e-09 4.692297e-01 4.463763e-02
12 1.462321e-09 5.320569e-01 4.656168e-02
13 1.641434e-09 6.052651e-01 4.953999e-02
14 1.999661e-09 7.391451e-01 5.660076e-02
15 2.000000e-09 7.392646e-01 5.660812e-02
16 2.000678e-09 7.389724e-01 5.662282e-02
17 2.002034e-09 7.383883e-01 5.665221e-02
18 2.004746e-09 7.372213e-01 5.671090e-02
19 2.010169e-09 7.348936e-01 5.682799e-02
20 2.021016e-09 7.302610e-01 5.706092e-02
21 2.042710e-09 7.210873e-01 5.752187e-02
22 2.086098e-09 7.031035e-01 5.842443e-02
23 2.172874e-09 6.685660e-01 6.015467e-02
24 2.346427e-09 6.049986e-01 6.333479e-02
25 2.693531e-09 4.977615e-01 6.871489e-02
26 3.387740e-09 3.458307e-01 7.648137e-02
27 4.044591e-09 2.575689e-01 8.118759e-02
28 5.083465e-09 1.773876e-01 8.567428e-02
29 6.388023e-09 1.282288e-01 8.844279e-02
30 7.744143e-09 1.014238e-01 8.957409e-02
31 9.091630e-09 8.498834e-02 8.972890e-02
32 1.044821e-08 7.518896e-02 8.931491e-02
33 1.221070e-08 7.151443e-02 8.842985e-02
34 1.492028e-08 8.126045e-02 8.741847e-02
35 1.831171e-08 1.055641e-01 8.804123e-02
36 2.201370e-08 1.303359e-01 9.141676e-02
37 2.622259e-08 1.500862e-01 9.762599e-02
38 3.076371e-08 1.692594e-01 1.060967e-01
39 3.587465e-08 1.965768e-01 1.177901e-01
40 4.198651e-08 2.347217e-01 1.353204e-01
41 5.065090e-08 2.902740e-01 1.663985e-01
42 6.015682e-08 3.551701e-01 2.077236e-01
43 7.678938e-08 4.821016e-01 2.961630e-01
44 9.377533e-08 6.231092e-01 4.049511e-01
45 1.276715e-07 9.366305e-01 6.649679e-01
46 1.893552e-07 1.563312e+00 1.232391e+00
47 2.529946e-07 2.190556e+00 1.856756e+00
48 3.108993e-07 2.701360e+00 2.389896e+00
49 3.595623e-07 3.087515e+00 2.796450e+00
50 4.107942e-07 3.460183e+00 3.187233e+00
51 5.097434e-07 4.094718e+00 3.853183e+00
52 6.097434e-07 4.636884e+00 4.423675e+00
53 6.982781e-07 5.016025e+00 4.840693e+00
54 7.768584e-07 5.359351e+00 5.174178e+00
55 8.540114e-07 5.654384e+00 5.486914e+00
56 9.295158e-07 5.922929e+00 5.763838e+00
57 1.001870e-06 6.151575e+00 6.006224e+00
58 1.101870e-06 6.444067e+00 6.308544e+00
59 1.201870e-06 6.703263e+00 6.580260e+00
60 1.301870e-06 6.663693e+00 6.685591e+00
61 1.401870e-06 5.913919e+00 6.272830e+00
62 1.481231e-06 5.204133e+00 5.600958e+00
63 1.573556e-06 4.825580e+00 4.994002e+00
64 1.654291e-06 4.874988e+00 4.852931e+00
65 1.691117e-06 4.934093e+00 4.884492e+00
66 1.727247e-06 4.979089e+00 4.927919e+00
67 1.773036e-06 5.024939e+00 4.980151e+00
68 1.821418e-06 5.048192e+00 5.021274e+00
69 1.868876e-06 5.055171e+00 5.043143e+00
70 1.929564e-06 5.046913e+00 5.049743e+00
71 2.006024e-06 5.034399e+00 5.041111e+00
72 2.106024e-06 5.023935e+00 5.028162e+00
73 2.203479e-06 5.024634e+00 5.024008e+00
74 2.303479e-06 5.026618e+00 5.025763e+00
... (126 more lines)
The circuit: examples/mosamp2.cir
mosamp2 - mos amplifier - transient m1 15 15 1 32 m w=88.9u l=25.4u m2 1 1 2 32 m w=12.7u l=266.7u m3 2 2 30 32 m w=88.9u l=25.4u m4 15 5 4 32 m w=12.7u l=106.7u m5 4 4 30 32 m w=88.9u l=12.7u m6 15 15 5 32 m w=44.5u l=25.4u m7 5 20 8 32 m w=482.6u l=12.7u m8 8 2 30 32 m w=88.9u l=25.4u m9 15 15 6 32 m w=44.5u l=25.4u m10 6 21 8 32 m w=482.6u l=12.7u m11 15 6 7 32 m w=12.7u l=106.7u m12 7 4 30 32 m w=88.9u l=12.7u m13 15 10 9 32 m w=139.7u l=12.7u m14 9 11 30 32 m w=139.7u l=12.7u m15 15 15 12 32 m w=12.7u l=207.8u m16 12 12 11 32 m w=54.1u l=12.7u m17 11 11 30 32 m w=54.1u l=12.7u m18 15 15 10 32 m w=12.7u l=45.2u m19 10 12 13 32 m w=270.5u l=12.7u m20 13 7 30 32 m w=270.5u l=12.7u m21 15 10 14 32 m w=254u l=12.7u m22 14 11 30 32 m w=241.3u l=12.7u m23 15 20 16 32 m w=19u l=38.1u m24 16 14 30 32 m w=406.4u l=12.7u m25 15 15 20 32 m w=38.1u l=42.7u m26 20 16 30 32 m w=381u l=25.4u m27 20 15 66 32 m w=22.9u l=7.6u cc 7 9 40pf cl 66 0 70pf vin 21 0 pulse(0 5 1ns 1ns 1ns 5us 10us) vccp 15 0 dc +15 vddn 30 0 dc -15 vb 32 0 dc -20 .model m nmos(nsub=2.2e15 uo=575 ucrit=49k uexp=0.1 tox=0.11u xj=2.95u + level=2 cgso=1.5n cgdo=1.5n cbd=4.5f cbs=4.5f ld=2.4485u nss=3.2e10 + kp=2e-5 phi=0.6 ) .control options acct abstol=10n vntol=10n tran 0.1us 10us print v(20) v(66) plot v(20) v(66) .endc .end
Run it with spice mosamp2.cir, or open it with File › Load netlist in the Qt window. The plots and output above were made by util/mkexamples.py, which runs the deck in batch mode. All examples