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I'm trying to implement the Schmitt trigger found in "CMOS" by J. Baker. Here's what the circuit should look like:

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And this is how the transistors should be dimensioned to achieve switching voltages of 0.7V and 0.4V:

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And here's what the output should look like:

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This is what my circuit and simulation results look like:

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As you can see, my Schmitt trigger doesn't switch at the correct voltages and the output is all lumpy.

In terms of troubleshooting, I have double-checked the connections and transistor dimensions. Also, I played around with the voltage source Vdc to see if I needed a larger voltage. Adjusting the voltage higher than 1Vdc breaks the circuit entirely.

Where have I gone wrong?

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I found this SCHMIDTT much more controllable

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ how do I dimension the transistors? with the same equations in my original post? \$\endgroup\$
    – suhh_drude
    Apr 25, 2018 at 14:08

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