Link design — electronic considerations

Abstract

Considering the transmitter and the receiver, the circuit that mainly determines the achievable transmission quality is the receiver front end. Here, the signal level is the lowest in the entire system, necessitating very low-noise operation. Further, the front end should combine a large gain and a large bandwidth, two requirements that are essentially conflicting. For these reasons, this chapter is entirely devoted to the front end. Throughout this chapter, it is assumed that the front end is a low-pass overall feedback amplifier. However, in principle, the design procedures are applicable to bandpass overall feedback amplifiers as well. Since the information-carrying signal is a current, the front end is either a transimpedance amplifier or a current amplifier. Because the general design philosophy has been published several times before, by Nordholt [66] and Verhoeven [67], this work only concentrates on those aspects essential to the design of wireless optical receivers.