Lecture5a - − − = = Approximately 1 period between...

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Lecture 5. DIODE CIRCUITS Objectives: Topics: Describe operation of rectifiers and power supplies Find output voltages of rectifiers and power supplies Describe demodulation using diode circuits Rectifiers Power Supplies Amplitude Demodulation
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Half-Wave Rectifiers D 1 ON: D 1 OFF: - works similar to a limiter (chops off voltages less than V f ) The transfer characteristic V OUT V IN Output voltage is 1 diode drop below the input voltage
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EXAMPLE Half-wave rectifier, R L =1k , V f =0.7V, triangular wave input (V peak =10V). Sketch v L , i L . Find v DC V t 10V i t dc signal=average over one period If x – periodic signal = T xdt T x 0 1 T Integral = area under the curve V t
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Bridge Rectifiers a)V IN –pos. b)V IN – neg. The transfer characteristic V OUT V IN V t 10V T Output voltage is 2 diode drops below the input voltage
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Power Supply Circuits - usually a rectifier combined with a filter (and voltage regulator) Half-Wave Rectifier Power Supply EXAMPLE. V IN – 12V rms, 60Hz sin, R L =200 , C=1mF. V ripple -? V ripple Capacitor Discharging: V P C R t f P OUT C L e V V V V / ) (
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Unformatted text preview: − − = = Approximately 1 period between points A and B Full-Wave Power Supply a)V IN – pos. b)V IN – neg. - use a bridge rectifier or a transformer with a center tap V P-V f V P- less ripple (peaks are closer) C R t f P OUT C L e V V V V / ) ( − − = = What is we used a bridge rectifier? Non-Resistive Load V MAX V MIN- capacitor discharging equation: C R t MAX C L e V V / − = What if R L is unknown (but we have i L )? When C discharges Voltage Regulation- use Zener regulator to eliminate ripple V t V ps Choose: R -V ZK-Amplitude Demodulation V t V m V s V m – signal to be transmitted (T m =10ms) Modulated signal (f C =1MHz) : Received signal needs to be demodulated Get the original rectangular wave using this circuit: Input to the filter Time constant RC affects the speed of discharging Choose RC logarithmically between T m and T C If T m =10ms, T C =1 µ s, choose:...
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This note was uploaded on 06/30/2010 for the course EECE 315 taught by Professor Nikulin during the Fall '08 term at Binghamton.

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Lecture5a - − − = = Approximately 1 period between...

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