Advanced Analog Circuits
Seth Price
Department of Chemical Engineering
New Mexico Tech
Rev. 1/26/15
Diodes (PN Junction)
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Diodes conduct in only one direction
Semiconducting device
Resistance is non-linear
Require a “knee” or “turn-on” voltage
– Silicon: 0.6-0.7V
– Germanium: 0.3V
– LED: 1.7V
Diode Vs. Sine Wave
• http://www.duncansonelectric.com/blog/wpcontent/uploads/2009/08/23-half-wave-rectifier-1024x368.gif
IV Curve for Diodes
https://learn.sparkfun.com/tutorials/diodes/real-diode-characteristics
Zener Diode
• Diode that is meant to operate in reverse bias
region
– Very stable, consistent voltage
• Can be used to replace battery, complex
resistor network in some situations
Capacitors
• Store energy in an electric field
• Measured in Farads (F)
• Two physical configurations
– Parallel plates
– Concentric cylinders
Capacitor Combinations
• Series Combination:
• 1/Ceq = 1/C1 + 1/C2 + … + 1/Cn
• Parallel Combination:
• Ceq = C1 + C2 + … + Cn
Capacitor Voltage
Vc(t) = Vs(1-e-t/T)
• Vc(t): Voltage across
capacitor at any time
• Vs: Source voltage
• T: Time constant
• t: elapsed time
Inductors
• Store energy in a magnetic field
• Measured in Henries (H)
• Typically a coil of wire
• Adjustable inductor: slug
Inductor Combinations
• Series Combinations
• Leq = L1 + L2 + … + Ln
• Parallel Combinations
• 1/Leq = 1/L1 + 1/L2 + … + 1/Ln
Inductor Voltage
V(t) = -L * di/dt
• V(t): Voltage across
Inductor as a function of
time
• L: inductance in Henries
• di/dt: change in current
with respect to time
Time Constants
• Time Constant (T): way to characterize time to
charge/discharge a capacitor or inductor
• 1*T: 63% of the maximum charge
• 5*T: fully charged
• For a capacitor: T = R*C
• For an inductor: T = L/R
Solenoids
• Changing current induces magnetic field
• Magnetic field moves plunger
• Used in starter motors, valves, latches, etc.
Solenoid Valve
Transformers
• Two adjacent inductors that can
influence each other
• Can add an iron core to transformer
to increase magnetic field
• No electron travels between
inductors
– Isolation Transformer
Transistors
• Semiconducting device
• Used as switches, amplifiers, attenuators,
impedance matching, etc.
• Two major categories (NPN, PNP)
• Types: BJT, MOSFET, JFET, etc.
Putting it all together…
• DC Power Supply