- INHIBIT Gate Definition: An INHIBIT gate is a logic gate that provides a constant output regardless of the changes in other inputs, controlled by a specific INHIBIT input.
- Understanding the Function: This gate typically locks the output based on one input being fixed, often inhibiting the normal function of a logic gate like NOR or AND.
- Circuit Symbol: The circuit symbol for an INHIBIT gate helps visualize its operational logic and the role of each input.
- Truth Table Clarification: The truth table for an INHIBIT gate illustrates how different input combinations affect the output, crucial for understanding gate behavior.
- Example Usage: An example provided shows that fixing an input at high logic level in a NOR gate configuration results in a consistent low output, demonstrating the INHIBIT functionality.
Earlier pages covered the usual gates in digital electronics: the basic AND gate, OR gate and NOT gates, plus NAND, NOR, XOR and XNOR. An INHIBIT gate adds a control pin that can freeze the output. Designers use that pin when a path must stay quiet unless a separate enable is true.
The inhibit pin, when asserted, forces a fixed output. The other pins do not get a vote until inhibit is released. Example: a four-input NOR gate with one input held at logic ‘1’.
That NOR output stays ‘0’ for every pattern on the free pins, because one input is already ‘1’. Hold that pin at ‘1’ and the NOR function is blocked. Bring it back to ‘0’ and the same circuit is a normal NOR gate again.
The same idea appears in an integrated circuit AND: invert one pin of an AND gate and that pin becomes inhibit. The remaining pins AND as usual only while inhibit sits at ‘0’. The circuit symbol and truth table below are a four-input INHIBIT gate.
In that drawing, if A, B and C sit at ‘1’, then inhibit ‘0’ yields Y = ‘1’ and inhibit ‘1’ yields Y = ‘0’. The table below lists every input combo for that gate.
| A | B | C | D | Y |
| 0 | 0 | 0 | 0 | 0 |
| 0 | 0 | 0 | 1 | 0 |
| 0 | 0 | 1 | 0 | 0 |
| 0 | 0 | 1 | 1 | 0 |
| 0 | 1 | 0 | 0 | 0 |
| 0 | 1 | 0 | 1 | 0 |
| 0 | 1 | 1 | 0 | 0 |
| 0 | 1 | 1 | 1 | 0 |
| 1 | 0 | 0 | 0 | 0 |
| 1 | 0 | 0 | 1 | 0 |
| 1 | 0 | 1 | 0 | 0 |
| 1 | 0 | 1 | 1 | 0 |
| 1 | 1 | 0 | 0 | 0 |
| 1 | 1 | 0 | 1 | 0 |
| 1 | 1 | 1 | 0 | 1 |
| 1 | 1 | 1 | 1 | 0 |
