The signal to noise ratio of a pin-photodiode is given by: 

SNR = i²_p/2eB(I_p + I_d) + 4kBT/R + B₁²_a

A NRZ pulse modulated signal with a bit rate, BT of 150 MB/s is transmitted over a 30 km long single mode fibre link. To ensure the required bit-error-rate for the system, the signal-to noise ratio at the receiver must be 20 dB. The receiver is a transimpedance amplifier with an open loop gain of 200. The average amplifier noise current is 2.2 pA/(Hz)1/2, the amplifier input resistance is 10 kohm and the feedback resistor is 10 kohm. The photodiode has a junction capacitancel of 7 pF .

1 Calculate the minimum photocurrent for the diode to maintain the required SNR (12) 3

2 Determine if the maximum bandwidth for the receiver and amplifier is larger than the required bandwidth.

Answer rating: 100% (QA)

Solution Gniven R 300 MBS 50 Km Pi 3 d Bm Fiber cable losses D25 ... View the full answer