(1) A photo receiver is to detect a 0.75 μW optical signal with a BER of 10-⁹ (SNR=144) or better. The filter before the
Posted: Thu May 26, 2022 10:42 am
(1) A photo receiver is to detect a 0.75 μW optical signal with a BER of 10-⁹ (SNR=144) or better. The filter before the decision circuit has a noise bandwidth of 150 MHZ. A PIN diode which has a responsivity of 0.8 A W1, a dark current of 1 nA and a capacitance of 4 pF is used as the detector. The photocurrent supplies a load resistor. The voltage developed across the load resistor is amplified by a wideband amplifier which contributes negligible noise, whose input resistance is 100 k and has an input capacitance of 3 pF. Show by appropriate calculations that this receiver design is currently not capable of satisfying the required performance. [8 marks]