A highly sensitive balanced receiver for 2.5 Gb/s heterodyne detection systems

A highly sensitive balanced receiver consisting of a high electron mobility transistor (HEMT) preamplifier, applying inductive peaking techniques and a newly designed optical front-end coupler, is proposed for 2.5-Gb/s heterodyne detection systems. A 8.7-pA/ square root Hz averaged equivalent input noise current density and over 23-dB common mode rejection ratio from 2 to 8 GHz were achieved. A 2.5-Gb/s CPFSK heterodyne detection with 66 photon/bit was carried out. The power penalties due to thermal noise and relative intensity noise were confirmed to be only 0.22-dB and under 0.08-dB, respectively.<<ETX>>