A very gentle intro

The invention that changed everything… The real thingCircuit diagram symbol

What transistors are good for ~731M transistors in Intel core i7

Transistor action: BJT BJT = Bipolar Junction Transistor Goal: control current flow from collector to emitter via base Fluid Analogy: Small signal controls a much larger signal

Transistor action: electron flow N N P Emitter Base Collector For conventional current flow (tracking positive charge movement), flip the arrows!

Bipolar Transistor Parameters BE: fwd biasBC: rev bias

Input characteristic Transistor ON  Fwd biased diode Working on the steep part of the curve (blue dotted box highlights normal operating range)   V BE small   I B relatively large * Rule of thumb: use V BE ~ 0.7V when designing BJT circuits IBIB V BE IBIB

Output Characteristic Active region (light blue): I c =  I B I c ~independent of V CE Saturation (yellow-ish): I c depends on V CE and I B 0.3V

Load Line 1. KVL in loop through transistor give us the load line 2. One point for saturation: V CE = 0, I c is maxed 3. One point for cutoff : I c = 0, V CE is maxed 4. Operating point: intersection of load line and characteristic curve

Load Line Example V CC = 10 V R L = 400  V LED = 1.6 V (red) Assume I B  1. 0 = V CC – V LED – I C R L – V CE 2. V CE = 0  I C = (V CC – V LED )/R L = 21.0 mA 3. I C = 0  V CE = V CC - V LED = 8.4 V

Load Line for example circuit  Actual current will be about 18 mA, a little less than designed for, but not bad!

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