Inverters#
Definition: Inverter
An inverter or NOT gate is a logic gate which computes negation.
Notation
The following symbols are use for inverters:
Here is the truth table for this gate:
| \(A\) | \(\mathop{\operatorname{NOT}}(A)\) |
|---|---|
| \(0\) | \(1\) |
| \(1\) | \(0\) |
CMOS Inverter#
An inverter can be implemented using CMOS in the following way:
The source of the PMOS is connected to a voltage source which ideally supplies a constant voltage, while the source of the NMOS is connected to ground. The drains of the MOSFETs are connected to another.
To see why this circuit behaves like an inverter, we need to analyze it:
TODO: Analog Analysis
In summary, the digital behavior is the following:
| \(V_{\text{in}}\) | PMOS | NMOS | \(V_{\text{out}}\) |
|---|---|---|---|
| \(0\) | conducting | non-conducting | \(1\) |
| \(1\) | non-conducting | conducting | \(0\) |