TAMS / Java / Hades / **applets** (print version): contents | previous | next#### AOI and OAI complex gates

**Description**

A demonstration of a few **complex logic gates**,
namely the OR-AND-INVERT and OR-AND-INVERT gates.

Click the input switches to toggle the corresponding input value
between 0 and 1, and watch the resulting behaviour.
You can also use shift+click to toggle the input value between
the states 0, 1, Z (tri-state, not driven) and X (undefined).

The names of these gates are derived from their AND-OR-INVERT and
OR-AND-INVERT structure and the number of inputs of the first level gates.
To give another example, an OAI222 gate (not shown in the applet)
is equivalent to three two-input OR gates that drive a three-input
NAND gate.

Complex gates are often used in CMOS VLSI chip design
because they can be realized very efficiently,
based on clever combinations of series- and parallel-connected transistors.
For example, the AOI33 gate can be built using just 12 transistors,
while the corresponding discrete realization would require
4 transistors for the NOR gate, and 8 transistors for each AND3 gate
for a total of 20 transistors - almost twice as expensive and twice
as slow.

Visit our
CMOS
technology applet page
for a detailed (switch-level) demonstration of a complex gate.

To explore the circuit, just click the corresponding switches,
or type the following keys:

- a,s,d (AOI21)
- f,g,h (OAI21)
- 1,2,3,4,5,6 (AOI33)
- y,u,i,o,p (OAI32)

(If typing the bindkeys does not work, please use one initial mouseclick
into the applet, to ensure that the simulator has the keyboard focus).

Run the applet | Run the editor (via Webstart)

Impressum | 24.11.06

http://tams.informatik.uni-hamburg.de/applets/hades/webdemos/10-gates/00-gates/complex_print.html