AND-OR-Invert (AOI) logic and AOI gates are two-level compound (or complex) logic functions constructed from the combination of one or more AND gates followed by a NOR gate. Construction of AOI cells is particularly efficient using CMOS technology where the total number of transistor gates can be compared to the same construction using NAND logic or NOR logic. The complement of AOI Logic is OR-AND-Invert (OAI) logic where the OR gates precede a NAND gate.
2-2 AOI gate
A B C D
2-1 AOI gate
The 2-1 AOI gate can be represented by the following boolean equation and truth table:
A B C
AND-OR-INVERT (AOI) and OAI gates can be readily implemented in CMOS circuitry. AOI gates are particularly advantaged in that the total number of transistors (or gates) is less than if the AND, NOT, and OR functions were implemented separately. This results in increased speed, reduced power, smaller area, and potentially lower fabrication cost. For example, a 2-1 AOI gate can be constructed with 6 transistors in CMOS compared to 10 transistors using a 2-input NAND gate (4 transistors), an inverter (2 transistors), and a 2-input NOR gate (4 transistors).
AOI gates are similarly efficient in transistor–transistor logic (TTL).
TTL 7400-series logic family: (in past decades, a number of AOI parts were available in the 7400 family, but currently most are obsolete)
- SN5450 = dual 2-2 AOI gate, one is expandable (SN54 is military version of SN74)
- SN74LS51 = 2-2 AOI gate and 3-3 AOI gate
- SN54LS54 = single 2-3-3-2 AOI gate
CMOS 4000-series logic family:
- CD4048B = single expandable 8-input 8-function gate, choice of: NOR, OR, NAND, AND, AND-NOR (AOI), AND-OR, OR-NAND (OAI), OR-AND
- CD4085B = dual 2-2 AOI gate
- CD4086B = single expandable "2-2-2-2 AOI gate"
- "SN74LS51 Datasheet". Texas Instruments. 1988. Archived (PDF) from the original on November 30, 2020.
- "SN5450 Datasheet". Texas Instruments. 1988. Archived (PDF) from the original on July 26, 2018.
- "SN54LS54 Datasheet". Texas Instruments. 1988. Archived (PDF) from the original on March 5, 2018.
- "CD4048B Datasheet". Texas Instruments. 2003. Archived (PDF) from the original on March 5, 2019.
- "CD4085B Datasheet". Texas Instruments. 2003. Archived (PDF) from the original on March 3, 2019.
- "CD4086B Datasheet". Texas Instruments. 2003. Archived (PDF) from the original on April 15, 2019.
- Tinder, Richard F. (2000). Engineering digital design: Revised Second Edition. pp. 317–319. ISBN 0-12-691295-5. Retrieved 2008-07-04.
- John, Michael (1997). Application-Specific Integrated Circuits. Retrieved 2008-07-04.