Analog Electronic Design :
The very first designs that came about were
analog designs, a Vacuum Tube amplifier is an example. Analog is the
representation of data or physical parameter in an accurate and precise
decimal
number like + 72.182 mV. The greater the resolution required, the more
demanding is the design for achieving high accuracy and low
drift. Digital
circuits have only
two voltage levels, high and low, the third state
of floating, Hi-Z or
high impedance is only for multiplexing or sharing a bus. This is done
so that devices dont drive into each other and it is also used in
external
port drivers.
As an analogy, see the conventional water tap as an analog control, an
electric light
ON-OFF switch as a digital control.
Even in digital, going from a low level say 0V to a high level say 5V
is
not instantaneous, the side of the square wave or the rising edge is
not as straight as it looks. On zooming only the edge, you see that it
is also an analog phenomena. The 'square wave' itself appears to be a
summation of
many sine waves, 'harmonics'. This is because nature is analog,
the sine wave is analog, the movements of the planets or even the
spin of electrons in an atom too. 
After the handheld Abacus calculator (low-power, durable,
bio-degradable), Mechanical and electro-mechanical computers were made
and studied, The very first electronic computers were Analog Computers using an
opamp as a building block.
Then came huge Digital
Computers, Later LSI and other Microelectronic Innovations have
precipitated handheld computers. An iPod Touch has a
Business-Scientific calculator and an Abacus as well.
The Rising edge of the square wave depends on the Transient
Response of the devices, the slew rate and bandwidth too. Fast Op-Amps
are
required for many applications, in switching and also AC amplification.
Beyond that, study goes into Power Electronics and RF-Microwave which
are specialized extensions of Analog. Similarly study of Digital
Circuits extends into Computers.
17:36 24-Oct-08
Anantha Narayan
|
