Photoconductive detectors have emerged to beome an important technology for lightwave communication since the recent demonstration of a Ga0.47In0.53As detector having a receiver sensitivity better than that of a Ga0.47In0.53Asp‐i‐nphotodiode. This study shows that the receiver sensitivity of a photoconductive detector compares fairly well with that of ap‐i‐nphotodiode (CT=1.0 pF) in the multigigabit rate regime. The calculated result is within 1.4 dB of our measurement data at 1 Gb/s, &lgr;=1.3 &mgr;m for a bit error rate of 10−9. This study further illustrates that noise in an undoped GaInAs photoconductive detector/field effect transistor front end system is dominated by the detector for bit rates less than 3 Gb/s.