EE 164 Problem Set 7

EE 164 Problem Set 7 - 10 P W = d V volts d iA Ap V − d V...

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EE 164 Problem Set 7 Spring 2005 Problem 1: Find the output current of a photodetector whose quantum efficiency is 0.9. The wavelength is 1.3 m µ , and the incident power lever is -37 dBm. Also, compute the resulting output voltage when the load resistance is 50 , 1000 , 1 M . Problem 2: Consider a PIN detector circuit in the below figure. The battery voltage is 10V, the load resistance is 2 M , the detector’s responsivity is 0.25 A/W, and the dark current is 0.5 nA. a) Draw the diode’s voltage-current characteristic in the photoconductive region for incident power levels ranging from 5 to 50 W and differing by 5 W . b) Draw the load line on the curve. c) Draw a curve of output voltage versus input optical power. d) At what value of the optical power does the detector saturate? Simple PIN circuit Ap V Graphical analysis of the circuit B L VR 10
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Unformatted text preview: 10 P W = ( ) d V volts ( ) d iA Ap V − + d V d i − + V L R Problem 3: Suppose that a PIN photodiode has a depletion width of 30 m , a carrier velocity of 4 5 10 × m/s, and a junction capacitance of 6 pF. a) Compute the transit-time-limited bandwidth. b) What is the largest load resistance that will not affect the bandwidth just calculated? c) What is the bandwidth if the load resistance is 10,000 Ω ? Problem 4: Consider the current-to-voltage converter in the below figure . The PIN detector has the respnsivity of 0.5 A W and the incident optical power is -34 dBm. The feedback resistance is 10 k Ω and the shunt capacitance of the feedback network is 0.2 pF. Compute a) The output voltage b) The 3-dB bandwidth d i d i 1 R 1 d v i R = − + − AB V + − Current to Voltage Converter...
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