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Wednesday, July 8, 2015

Discrete component electronics to Integrated Circuits - 50 years of change

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A very short summary of the 50 years -  From individual transistors used to make electronic circuits in 1965 to one integrated circuit (smaller than your thumbnail)  microprocessor chip containing 5.5 billion transistors in 2015.

The Integrated Circuit (IC) changed electronics in a very big way.  Jack Kilby demonstrated a working example for the IC made of germanium  in 1958 and six months  later  Robert Noyce demonstrated his own idea of the IC made of silicon that  solved many practical problems of producing an IC. The invention of the IC was a new way of building electronic circuits and Jack Kilby received the Nobel Prize in physics  in December 2000. These notes from Wikipedia.

A lesson in electronic circuit manufacturing prior to the IC.
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7 transistor Radio 
Transistors were invented in 1947 and became a practical amplifier design element in about 1957.

Here is a look at the inside of a 1965 transistor radio made with 7 transistors.

 In 2007 one large memory IC contained a sufficient number of transistors to make more than one billion of these radios.

7 transistor Radio
Looking closer at the inside of the transistor radio you see the 2 black transistors with 3 legs and a few resistors, capacitors and inductors.  These are all discrete components.

These discrete components can be replaced by circuitry in a single IC - and by the billions in the one IC. An IC can have manufactured into the chip - diodes, resistors, capacitors, and transistors. However the chip count is always just the number of transistors. As of 2015, the highest transistor count in a commercially available CPU (in one IC chip) is over 5.5 billion transistors - Intel's 18-core Xeon Haswell-EP.


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Vacuum tube amplifier
          Vacuum tubes were invented in 1904 by  John Ambrose Fleming and later individual transistors in 1947 invented by John Bardeen, Walter Brattain, and William Shockley are the amplifying element in all electronic circuits.
         This photo is an amplifier from an electronic instrument (Oscilloscope 1960) with about 36 tubes. The whole instrument had about 100 tubes. The amplifier is about 12 inchs by 12 inchs.
Transistors replaced vacuum tubes as amplifying devices in the 60's. Transistors are much smaller than vacuum tubes, use less power, generate less heat and in theory never wear out making circuits much smaller & use much less power.

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discrete components

The bottom of the amplifier containing all the needed resistors and capacitors needed to make the circuit operational.

This is called discrete component design because each part is a single  separate part - (resistor or capacitor in the design).

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Bugbook Computer Museum
Components by Khrulev Alexey E.

Examples of discrete components.

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resistors & capacitor - discrete components
Several discrete components in a circuit - resistors and capacitor wired together. The red device is the capacitor and is about 1/2 inch by 1/4 inch in size.

An IC smaller than the capacitor in 2005 contained more than a billion-transistors  on a single chip and in 2007  tens of billions of memory transistors on a single chip. I don't know what is available today, these numbers are just hard to imagine on a single chip.

Click on photo to enlarge 
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IC chip containing millions of transistors
ICs have two main advantages over discrete circuits: cost and performance. Cost is low because the chips, with all their components, are printed as a unit by photolithography rather than being constructed one transistor at a time. Furthermore, packaged ICs use much less material than discrete 2, with up to 9 million transistors per mm2. Performance is high because the IC's components switch quickly and consume little power (compared to their discrete counterparts) as a result of the small size and close proximity of the components. As of 2012, typical chip areas range from a few square millimeters to around 450 mm.
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Carol Milazzio

Some nice photos taken in our museum by Carol Milazzio KP4MD during a recent visit - "Take a look Click"

Bugbook Historical Microcomputer Museum
David Larsen
This blog post has been fun for me as a way to reminisce. I began to use vacuum tubes in 1952 as an amateur radio operator at 14 years old.  Later my teaching for 31 years at Virginia Tech started in 1967 with vacuum tubes and ended in 1998 using microcomputers. I experienced the whole range from tubes to large scale Integrated Circuits.
           ."by David Larsen"  KK4WW Computer Collector Historian