nMos, pMos 트랜지스터

트랜지스터는 '스위치'다.

 

Transistors

Two types of transistors

	nMos	pMos
behaves as an open switch when	Vg is low (0)	Vg is high
behaves as an closed switch when	Vg is high (1)	Vg is low

 

nMos Transistors

Act as a open switch when the gate voltage (Vg) is low

Meaning that current cannot flow between source and drain

Act as a closed switch when the gate voltage (Vg) is high

Meaning that current can flow between source and drain

pMos Transistors

Act as a closed switch when the gate voltage (Vg) is low

Meaning that current can flow between source and drain

Act as a open switch when the gate voltage (Vg) is high

Meaning that current cannot flow between source and drain

 

Building Logic Gates with Transistors

Designing an inverter

- inverter: Not Gate

- I want to design a circuit that takes as an input a one-bit value and outputs the complement of that number

 

Power and Ground

- power: a component that produces a logic high value (power = 1)

- ground: a component that produces a logic low value (ground = 0)

 

Logic Gate w/ transistors

- we use nMos transistors to connect the output to ground

- we use pMos transistors to connect the output to power

 

CMos Gates

- cMos = complementary MOS

- what is MOS? mental oxide semiconductor

- the pMos and nMos transistors complement each other to form the logic gate

- cMos is not a type of transistor! It's a technology that combines both pMos and nMos transistors

 

Pull-up and Pull-down Networks

- only one network will be on at a time

- the pull-up network drives the output when the output is 1

- the pull-down network drives the output when the output is 0

Switch

- switch in series: current can only flow btwn two ends if both switches are closed

current flow = switch 0 AND switch 1

 

- switch in parallel: current can flow btwn the two ends if either of the switches is closed

current flow = switch 0 OR switch 1

 

CMOS NAND

- pMos에서 0이면, current가 흐르니까 output으로 Vdd (1)이 전달된다. pMos 값이 1이면, current가 흐르지 않으므로 output으로 전달되지 않는다.

- nMos에서 1이면, current가 흐르니까 output으로 Gnd (0)이 전달된다. pMos 값이 0이면, current가 흐르지 않으므로 output으로 전달되지 않는다.

- pMos는 병렬로, nMos는 직렬로 만들어줘야 한다.

CMOS NOR, CMOS AND, CMOS OR

 

Transistor Count

Gate	Number of Transistors
NOT	2
AND	6
OR	6
NAND	4
NOR	4
XOR	12
XNOR	12