Circuits and Transistors

Circuit

closed path where electrons flow from a source of voltage or current

Source

origin of electrons

Ground

return path of electrons

Voltage (volts, V)

difference in electric potential between source(origin) and ground(return path)

Current (I) (amps, A)

rate of electrons flowing through a circuit

Resistance (ohms, 𝛀)

opposition to electrons flowing through a circuit

ohm’s law - V=IR

Analog signal

takes any continuous value

Digital signal

takes one of a discrete set of values

Binary signal

0 or 1

Digital Circuit

connection of components that takes digital inputs and produces digital outputs (binary digital signal)

Switch

• Source Input

• Control Input

• Output

Moore’s Law

number of transistors on an IC doubles about every 2 years

N - Channel MOSFET (nMOS)

• Vdd = Source Input

• Vin = Control input (apply 1 = circuit closed) (apply 0 = open circuit)

• Vss = Output

P - Channel MOSFET (pMOS)

• Vin = Control Input (apply 1 = open circuit) (apply 0 = closed circuit)

CMOS

• Complimentary Metal - Oxide - Semiconductor

• integrated circuit made from pairs of nMOS and pMOS transistors