Video - How Transistors Shaped Our Modern World and How They Work
Summary
Below is a summary of the topics covered in Real Engineering’s video. For the full effect and information including illustrations and examples, I recommend watching all the way through.
Transistors are one of the most important inventions that has transformed the world faster than ever before. Over 59% population currently connected to internet now, and this number is growing with lower cost and higher accessibility.
Without transistors, we would not have the internet, extensive connectivity, and everything that comes with this technology in it’s current form
History
Prior to transistors, we used vacuum tubes to accomplish the same goal.
A vacuum tube consists of an anode, a grid, and a cathode.
The vacuum tube works by passing a current through the cathode, heating it up and causing a release of electrons. The electrons are attracted to the positively charged anode on the other side of the grid. A positive voltage is considered a 1 and a negative voltage is considered a 0 in the operation. This is the origin of binary computing.
Early vacuum tube computers would have tubes burn out regularly.
Silicon
Modern transistors in your CPU are microscopic in size and are manufactured on thin silicon wafers.
Silicon is considered a semiconductor, allowing us to manipulate whether or not it can conduct electricity. A perfect silicon crystal consists of silicon atoms, with 4 electrons each, creating covalent bond with 4 other surrounding silicon atoms.
The N-P-N Transistor
N-Type Semiconductor – Adds a Phosphorus atom with 5 electrons, making the silicon crystal negatively charged.
P-Type Semiconductor – Adds a Boron atom with 3 electrons, making the silicon crystal positively charged.
N-P-N Transistor consists of 2 N-Type semiconductors sandwiching a P-Type semiconductor. The negative charges from the N-Type semiconductors create a “Negative Depletion Layer” which prevents additional electrons from passing through. When a positive charge is applied, the negative depletion layer is removed and electrons can pass through freely again.
Logic Gates
AND gate – Electric circuit that outputs a high voltage state if all inputs are high
OR gate – Electric circuit that outputs a high voltage state if one or more input is high
NOT gate – Electric circuit that outputs an inverted voltage state
NAND gate – Electric circuit consisting of an AND gate followed by a NOT gate
NOR gate – Electric circuit consisting of an OR gate followed by a NOT gate
EOR gate – Electric circuit that outputs a high voltage state when any, but not all inputs are high
ENOR gate – Electric circuit that outputs a low voltage state when any, but not all inputs are high
See more information on logic gates here
Moore’s Law
The co-founder of Intel, Gordon Moore, discovered in 1965 that the density of transistors manufactured in a circuit has doubled and will double every two years. This is considered “Moore’s First Law”.
Moore’s Second Law – The cost of manufacturing these higher density circuits will double every four years.
The current state of the semiconductor industry is realizing the limitations of Moore’s second law now, as manufacturers are having difficulty keeping up with the technological advances while still turning a profit.
Quantum Tunneling – Another limiting factor in reducing the size of transistors is due to the negative depletion layer getting so small that electrons are able to pass through sometimes.
What is the future of computing? How will computing continue to advance? Quantum mechanics? Internet of things?
The video was produced by Real Engineering. Check his channel out here:
For some additional electrical engineering resources, take a look at these posts:
How Things Work: How Does A MEMS Gyroscope Work?
Calculating Allowed Bow and Twist for Circuit Card Assemblies
