NOT Gate Dual-Output Inverter
A switch drives one light directly and a second through a NOT gate. The two visible outputs are complementary for either binary input state.
What You'll Learn
- Read the complete one-input, two-output truth table.
- Distinguish the direct monitor from the inverter output.
- Recognize the inversion bubble and write Inverted = ¬A.
- Verify that Direct and Inverted are always complements in stable states.
- Separate Boolean inversion from physical timing and drive behavior.
How It Works
The switch output fans out along two paths. One path drives the upper light directly, so that light displays Direct = A. The other path passes through a NOT gate before reaching the lower light, so it displays Inverted = ¬A.
For A = 0, the direct light is off and the inverted light is on. For A = 1, the direct light is on and the inverted light is off. The two outputs are therefore complementary and exactly one of the two lights is on for either binary input.
The direct branch is a monitor, not a second logic operation. The production graph contains one switch, one inverter, and two output lights—four non-text components in total.
A physical inverter also has finite delay and electrical drive characteristics. During a transition, the direct and inverted paths do not necessarily change at exactly the same instant, but this simulator view focuses on their stable Boolean states.
Truth Table
One switch drives two visible paths: Direct follows A, and Inverted equals ¬A.
| Inputs | Output | ||
|---|---|---|---|
| A | Direct | Inverted | |
| 0 | 0 | 1 | A = 0 — direct light off, inverted light on. |
| 1 | 1 | 0 | A = 1 — direct light on, inverted light off. |
Boolean Expression
The upper monitor is wired directly to the switch and therefore reproduces A.
The lower monitor is driven by the NOT gate and therefore displays the logical complement of A.
The two visible outputs are complements, so exactly one is high for either valid binary input.
Try It Step-by-Step
Set the listed controls in the embedded circuit, then compare the observed modeled state with the expected result.
- 1A=0Expected:
Direct = 0, Inverted = 1What you'll see:With the switch off, the upper direct path carries 0 and the lower inverter output carries 1. - 2A=1Expected:
Direct = 1, Inverted = 0What you'll see:With the switch on, the upper direct path carries 1 and the lower inverter output carries 0.
Components Used
Applications and Design Context
Active-low conversion. An inverter converts between active-high and active-low signal conventions.
Complement generation. Control logic may need both a condition and its complement for mutually exclusive paths.
Signal observation. Direct and inverted indicators provide a simple diagnostic view of polarity.
Clock and reset polarity adaptation. Carefully placed inversion can adapt interfaces that use opposite active polarities, subject to timing requirements.
Buffer chains. An even number of inverter stages restores the original polarity while providing staged electrical drive in a physical implementation.
Frequently Asked Questions
What does the small circle on an inverter symbol mean?
The small circle, or inversion bubble, denotes logical negation. An output bubble means the signal leaving that symbol is complemented.
Is a buffer the same as a NOT gate?
No. A buffer preserves the logic value while providing electrical drive; an inverter complements it. Two inverters in series restore the original logic polarity and can form a noninverting buffer stage.
How is inversion implemented in CMOS?
A conventional static-CMOS inverter uses a complementary PMOS pull-up and NMOS pull-down. Other logic families and specialized topologies can realize inversion differently.
What is the inverter's propagation delay?
It depends on process, supply, transistor sizing, input slew, output load, interconnect, and the characterized cell. This logic-level schematic does not define a numerical propagation delay.
Why are there two output lights?
The upper light is connected directly to the switch, while the lower light is connected to the NOT output. Showing both paths makes the complementary relationship observable; a minimal inverter test could omit the direct monitor.