On the lateral NPN, the substrate node should be tied to the highest voltage. On the vertical NPN, it should be tied to the lowest voltage.
Experimentation:
Simulate both circuits during 4e-7 seconds with a communication interval of 5e-9 seconds. Plot the input and output voltages, vin and vout, together on one graph. Plot the power dissipated by the two non-linear current sources, Pel, in a separate plot window.
Simulation Results:
You should obtain the following graph:
The red curve shows the output voltage for the circuit using the laterally diffused NPN, the green curve shows the same voltage for the circuit using the vertically diffused NPN. They differ primarily during their initialization. Their analog inversion characteristics are almost identical.
Notice the use of the ramping voltage sources, used also on the two DC supplies. Without the use of ramping sources, both circuits would exhibit violent high-frequency transient responses initially.
The power dissipated by the two non-linear (internally modulated) current sources is indeed always positive:
as proven in [1,2].
References:
| Name | Description |
|---|---|
| NPNlateral | Simple inverter circuit using a laterally diffused NPN transistor |
| NPNvertical | Simple inverter circuit using a vertically diffused NPN transistor |