Sensitivity limits of long-wavelength monolithically integrated p-i-n JFET photoreceivers

Noise characteristics and factors which limit the sensitivity of long-wavelength monolithically integrated photoreceivers using InGaAs p-i-n photodiodes (PD) and InGaAs junction-held-effect transistors (JFET´s) were analyzed with regard to the input-noise current and the open-loop gain. Effects of the JFET gate length and the parasitic capacitance on the sensitivity were also clarified. Three types of photoreceivers were fabricated by using metal organic vapor phase epitaxy (MOVPE)-grown crystals and Be-ion implantation technology. The receiver using a cascode input stage had an extremely high sensitivity (-35.4 dBm) for a 622-Mb/s NRZ, 13-μm-wavelength signal. The sensitivity of the other two receivers using an inverter input stage was moderate, -33.6 dBm for a multipower supply input stage and -31.4 dBm for a single power supply input stage