ECL-compatible Schmitt trigger
Transient response of a bipolar Schmitt trigger to a slow ramp.
An emitter-coupled Schmitt trigger driven by a slow ramp, showing the switching thresholds and hysteresis.
- v(1)
- v(3)
- v(5)
- v(6)
Output
schmitt ckt - ecl compatible schmitt trigger
Transient Analysis Tue Sep 29 08:47:04 2026
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Index time v(1) v(3) v(5)
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0 0.000000e+00 -1.600000e+00 -2.596995e-01 -1.220586e+00
1 1.000000e-10 -1.600000e+00 -2.596990e-01 -1.220584e+00
2 2.000000e-10 -1.600000e+00 -2.596991e-01 -1.220584e+00
3 4.000000e-10 -1.600000e+00 -2.596987e-01 -1.220582e+00
4 8.000000e-10 -1.600000e+00 -2.596993e-01 -1.220586e+00
5 1.600000e-09 -1.600000e+00 -2.596994e-01 -1.220586e+00
6 3.200000e-09 -1.600000e+00 -2.596996e-01 -1.220586e+00
7 6.400000e-09 -1.600000e+00 -2.596994e-01 -1.220586e+00
8 1.000000e-08 -1.600000e+00 -2.596996e-01 -1.220587e+00
9 1.064000e-08 -1.599360e+00 -2.596839e-01 -1.220564e+00
10 1.192000e-08 -1.598080e+00 -2.596768e-01 -1.220556e+00
11 1.448000e-08 -1.595520e+00 -2.596824e-01 -1.220565e+00
12 1.960000e-08 -1.590400e+00 -2.596815e-01 -1.220575e+00
13 2.960000e-08 -1.580400e+00 -2.596832e-01 -1.220568e+00
14 3.960000e-08 -1.570400e+00 -2.596818e-01 -1.220573e+00
15 4.960000e-08 -1.560400e+00 -2.596841e-01 -1.220570e+00
16 5.960000e-08 -1.550400e+00 -2.596829e-01 -1.220573e+00
17 6.960000e-08 -1.540400e+00 -2.596855e-01 -1.220570e+00
18 7.960000e-08 -1.530400e+00 -2.596853e-01 -1.220573e+00
19 8.960000e-08 -1.520400e+00 -2.596900e-01 -1.220576e+00
20 9.960000e-08 -1.510400e+00 -2.596920e-01 -1.220581e+00
21 1.096000e-07 -1.500400e+00 -2.596990e-01 -1.220585e+00
22 1.196000e-07 -1.490400e+00 -2.597053e-01 -1.220592e+00
23 1.296000e-07 -1.480400e+00 -2.597179e-01 -1.220600e+00
24 1.396000e-07 -1.470400e+00 -2.597306e-01 -1.220602e+00
25 1.496000e-07 -1.460400e+00 -2.597579e-01 -1.220627e+00
26 1.596000e-07 -1.450400e+00 -2.597905e-01 -1.220645e+00
27 1.696000e-07 -1.440400e+00 -2.598451e-01 -1.220687e+00
28 1.796000e-07 -1.430400e+00 -2.599206e-01 -1.220738e+00
29 1.896000e-07 -1.420400e+00 -2.600347e-01 -1.220820e+00
30 1.996000e-07 -1.410400e+00 -2.602055e-01 -1.220939e+00
31 2.096000e-07 -1.400400e+00 -2.604550e-01 -1.221117e+00
32 2.196000e-07 -1.390400e+00 -2.608310e-01 -1.221379e+00
33 2.296000e-07 -1.380400e+00 -2.613922e-01 -1.221776e+00
34 2.396000e-07 -1.370400e+00 -2.622467e-01 -1.222375e+00
35 2.496000e-07 -1.360400e+00 -2.635621e-01 -1.223300e+00
36 2.596000e-07 -1.350400e+00 -2.656485e-01 -1.224759e+00
37 2.696000e-07 -1.340400e+00 -2.691132e-01 -1.227174e+00
38 2.796000e-07 -1.330400e+00 -2.754600e-01 -1.231549e+00
39 2.896000e-07 -1.320400e+00 -2.904841e-01 -1.241656e+00
40 2.908500e-07 -1.319150e+00 -2.937876e-01 -1.243773e+00
41 2.933500e-07 -1.316650e+00 -3.022094e-01 -1.249003e+00
42 2.983500e-07 -1.311650e+00 -3.530669e-01 -1.278489e+00
43 3.030519e-07 -1.306948e+00 -6.867711e-01 -1.457228e+00
44 3.066175e-07 -1.303382e+00 -7.825546e-01 -1.646159e+00
45 3.086648e-07 -1.301335e+00 -7.462956e-01 -1.562625e+00
46 3.095193e-07 -1.300481e+00 -7.627595e-01 -1.590204e+00
47 3.103959e-07 -1.299604e+00 -7.618451e-01 -1.592830e+00
48 3.113144e-07 -1.298686e+00 -7.588767e-01 -1.588691e+00
49 3.126185e-07 -1.297382e+00 -7.627169e-01 -1.591697e+00
50 3.139792e-07 -1.296021e+00 -7.595478e-01 -1.590440e+00
51 3.167005e-07 -1.293299e+00 -7.630220e-01 -1.591403e+00
52 3.207463e-07 -1.289254e+00 -7.609723e-01 -1.591736e+00
53 3.280031e-07 -1.281997e+00 -7.648637e-01 -1.592832e+00
54 3.380031e-07 -1.271997e+00 -7.640980e-01 -1.594271e+00
55 3.480031e-07 -1.261997e+00 -7.683091e-01 -1.595595e+00
56 3.580031e-07 -1.251997e+00 -7.676873e-01 -1.597164e+00
57 3.680031e-07 -1.241997e+00 -7.717551e-01 -1.598369e+00
58 3.780031e-07 -1.231997e+00 -7.712724e-01 -1.600045e+00
59 3.880031e-07 -1.221997e+00 -7.752031e-01 -1.601152e+00
60 3.980031e-07 -1.211997e+00 -7.748540e-01 -1.602915e+00
61 4.080031e-07 -1.201997e+00 -7.786539e-01 -1.603945e+00
62 4.100000e-07 -1.200000e+00 -7.771409e-01 -1.604691e+00
63 4.110000e-07 -1.200000e+00 -7.779972e-01 -1.604537e+00
64 4.130000e-07 -1.200000e+00 -7.781318e-01 -1.604610e+00
65 4.170000e-07 -1.200000e+00 -7.780143e-01 -1.604570e+00
66 4.250000e-07 -1.200000e+00 -7.781239e-01 -1.604598e+00
67 4.350000e-07 -1.200000e+00 -7.780187e-01 -1.604576e+00
68 4.450000e-07 -1.200000e+00 -7.781200e-01 -1.604592e+00
69 4.550000e-07 -1.200000e+00 -7.780225e-01 -1.604581e+00
70 4.650000e-07 -1.200000e+00 -7.781164e-01 -1.604588e+00
71 4.750000e-07 -1.200000e+00 -7.780259e-01 -1.604585e+00
72 4.850000e-07 -1.200000e+00 -7.781131e-01 -1.604585e+00
73 4.950000e-07 -1.200000e+00 -7.780291e-01 -1.604588e+00
74 5.050000e-07 -1.200000e+00 -7.781147e-01 -1.604586e+00
... (240 more lines)
The circuit: examples/schmitt.cir
schmitt ckt - ecl compatible schmitt trigger .width in=72 .opt acct list node lvlcod=2 vin 1 0 pulse(-1.6 -1.2 10ns 400ns 400ns 100ns 10000ns) vee 8 0 -5 rin 1 2 50 rc1 0 3 50 r1 3 5 185 r2 5 8 760 rc2 0 6 100 re 4 8 260 rth1 7 8 125 rth2 7 0 85 cload 7 0 5pf q1 3 2 4 qstd off q2 6 5 4 qstd q3 0 6 7 qstd q4 0 6 7 qstd .model qstd npn(is=1.0e-16 bf=50 br=0.1 rb=50 rc=10 tf=0.12ns tr=5ns + cje=0.4pf pe=0.8 me=0.4 cjc=0.5pf pc=0.8 mc=0.333 ccs=1pf va=50) .control tran 10ns 1000ns print v(1) v(3) v(5) v(6) plot v(3) v(5) v(6) v(1) .endc .end
Run it with spice schmitt.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