Transistors
Amplifier
A device that provides amplification without significantly altering the shape of the original signal.
Transistor
A semiconductor device, usually made of silicon or germanium that amplifies by controlling the current carriers through the semiconductor materials.
VCC
Collector Supply
VCE
Collector to Emitter voltage. Represents the voltage dropped across the entire transistor.
A transistor is a _____ controlled device.
Current
F.I.R.E
F-Forward Bias (↑) I- Current flow (↑) R- Junction Resistance (↓) E- Voltage drop of transistor (↓)
Emitter Resistance (RE)
Forms voltage divider with resistance of Emitter-Base junction of Q1. Provides proper bias voltage for the junction from Emitter supply VEE.
Common Emitter
Input is on Base, output is on Collector.
Common Collector
Input is on Base, output is on Emitter.
Common Base
Input is on emitter, Output is on Collector.
Injection
Majority carriers from emitter are made to cross the emitter-base junction and flow as minority carriers in the base.
Diffusion
Majority carriers injected into base from emitter become minority carriers in the base, moving from an area of high concentration to a region of low concentration.
Collection
Minority carriers from base are diffused across the collector base junction, becoming majority carriers in the collector.
Emitter (characteristics)
Most heavily doped of the three elements. Identified by arrowhead on the symbol. Arrow points towards N-type material
Two types of transistors
PNP and NPN
Collector (characteristics)
Physically the largest element Physically large area allows for heat dissipation.
Amplification
The process of increasing the strength of a signal. (May be an increase in voltage, power, or current of a signal.)
Base (characteristics)
Thinnest transistor element Lightest doping of the three elements Permits most current carriers to reach the collector
Emitter
base junction is forward biased. (low resistance)
Collector
base junction is reverse biased. (high resistance)