Question

Q.14 a) i A silicon p-i-n photodiode incorporated into an optical receiver has a quantum efficiency of 60 % at a wavelength of 0.9 um The dark current is 3 nA and load resistance is 4 Kn. The incident optical power is 200 nw and the receiver bandwidth is 5 MHz. Determine 1) Mean square quantum noise current, 2) Mean square dark current and 3) Mean square thermal nosie current at a temperature of 20 °C [8]

Answer 1

Griveu 0.9m 90.9 X10 k aurkutI,= 89A - 3x10 A RI (Load curnnt incidence incidut optcal pouea) 200 nw 20OALő'w V's0)Xt7 34 J-S Planles constamt= 6'65 x10 h ecieuey 2-0.6 Bomdwidtn SMHZ =SX106N2 = 1-6X10 ev Meer Square quaulum noise cuvndt 2 Pinciduses 0.9 x11.6X1019)xo 9A10x200xI 6.65 X101 x 3X108 3.6 X 10 Amp 2Mean dquare dae cwent 2(B-w) 2x1-6x103x 10xx10 Anmp 48 x 10 3) Mean Squane thmal meix eurunt at a 4KTR RL tenup of T-204273) 293K. 4X1.38 x10 x29% x 20x10 A000 .22 x 10 Aup