The EDR 51xx Series incorporates a 75 m InGaAs PIN photodetector coupled with a low cost BiCMOS transimpedance amplifier (TIA) designed to operate at 155 Mb/s (EDR 512x) or 622 Mb/s (EDR 515x). The PIN transduces optical power into current with high efficiency. The TIA converts the current signal into a voltage signal with a very low input noise current contribution. The EDR 512x TIA also integrates an automatic gain control (AGC) circuit which decreases the light to voltage conversion factor when the average incident optical power is relatively high.