Design of an optically frequency or phase‐controlled oscillator for hybrid fiber‐radio LAN at 5.2 GHz

Abstract

International audienceWe propose the design of a transceiver directly converting an OOK optical signal into a microwave carrier that is either FSK or PSK modulated. The transceiver consists of a microwave oscillator based upon a silicon-germanium (SiGe) heterojunction phototransistor (HPT). The simulations show that a binary rate of 200 Mb/s is possible for a carrier of 5.2 GHz and reaches 1 Gb/s with a carrier at 12 GHz

Design and realization of an optically controlled oscillator for radio over fiber at 5.2 GHz

“…The oscillation frequency decreases significantly in approximately 10 ns, then decreases slowly before stabilisation. This behaviour is compatible with a 100 Mbps digital frequency modulation (FSK), with a correct eye pattern, as we have presented in [4]. Both simulation results concern a 5.2 GHz photooscillator designed in .35 µm AMS technology, which appears as suitable for our application.…”

“…The effect of light on the phototransistor is modeled by a current source in parallel with the intrinsic base-tocollector junction in the large-signal Gummel-Poon model [3,4]. This photocurrent I PH is related to the optical power P opt by I PH = S.P opt (1) Where S is the responsivity, given by the expression :…”

“…In order to implement the HPT model on the simulation software Agilent ADS2002C, we start from the foundry-compiled electrical model of the transistor and we follow the method we describe in [4], inserting the photocurrent and taking in account the modification of some extrinsic parameters due to the window opening.…”

SiGe heterojunction bipolar phototransistor for optics–microwaves interfacing

“…It allows the design of a photo-oscillator whose frequency decreases when the optical power increases, which was demonstrated by simulation [4]. t 1 decreases when I c increases (t 2 , which is an Resistance-Capacitor (RC) time constant, remains nearly constant).…”

“…It can be used in the new receiver structure for optics-microwave interfacing in radio-over-fiber networks we have previously proposed [4]. It can be used in the new receiver structure for optics-microwave interfacing in radio-over-fiber networks we have previously proposed [4].…”