Bandwidth boosting in transimpedance amplifiers for optical LANs, using delayed feedback

N. Martins, Luis Barbosa, Luís Nero Alves, Rui L. Aguiar

Abstract: Delayed-feedback amplifiers are composed of, a forward gain amplifier, a feedback network and a time-delay element. Recently published results [1] claim the possibility of bandwidth enhancement for this type of systems, simply by a judicious choice of loop-gain, open loop poles and the net time-delay. This paper describes the design steps for a shunt-shunt feedback amplifier with an active delay on the feedback loop. The designed circuit was optimized for Free-Space Optical (FSO) line-of-sight receivers. Achieved results show that the inclusion of the active delay, improve bandwidth in a maximum of 60%. A maximum of 1.5THzΩ GBW (11Ωk transimpedance gain) was achieved with a photodiode having intrinsic capacitance of 100pF.