Basic Structure
Electrical behavior
Chapter 3 Digital circuit
Basic CMOS gates
Any node must get 1/0 from
Vcc/Gnd by switches
Switch is made by MOS device
MOS device
Switch is controlled by G through electric field;
On,RD-S is low; Off,RD-S is high;
PMOS,when G is 0,Switch on;
when G is 1,Switch off;
NMOS,when G is 1,Switch on;
when G is 0,Switch off;
Two types of MOS device
CMOS inverter
F,get 1 from PMOS,get 0 from NMOS;
When X=1,NMOS is on;
When X=0,PMOS is on;
Why must be complementary?
NAND gate / NOR gate
NAND,NMOS serial,PMOS parallel;
NOR,NMOS parallel,PMOS serial;
NAND gate / NOR gate
Each input control a PMOS and an NMOS;
AND -- series OR -- parallel
Logic is represented by NMOS connections,
PMOS is a duality connection.
AOI / OAI
Summery for basic CMOS
Each input is connected both NMOS and PMOS;
The logic is expressed in N net,P net is its duality;
The output is a negative logic !
More examples
Output of the positive logic
Buffer AND gate
Add an inverter to the inverse output !
CMOS transmission gate
Three state output,0 / 1 / Z
When c=1,signal is passed
When c=0,signal is cutoff
Three state buffer Three state inverter
Circuit made by three-state devices
XOR gate Simple Multiplexes
Open gate and wired logic
The gate can only output 0/Z;
The output can be connected to get AND logic ;
The output can get 1 by pull-up resistors.