An HBT preamplifier for 40-Gb/s optical transmission systems

Abstract

30,. I 6 1 U + I ._ 20: 3 7 J 1 0 -m Abistract-A preamplifier for 40-Gb/s optical transmission systems has been constructed using AIGaAdInGaAs HBTs with p+ regrown extrinsic base layers. This preamplifier achieved a bandwidth of 34.6GHz and a transimpedance gain of 41.6dB0. This is the widest bandwidth in a preamplifier ever reported. These characteristics are suitable for use in a 40Gb/s optical receiver. The results indicate that AIGaAsDnGaAs HBTs with p+ regrown extrinsic base layers are very promising for production of 406b/s optical transmission systems. -RB -XF I INTRODUCTION1 Ol-Gb/s optical transmission systems are becoming widely used. Higher ultra-speed and higher ultra-capacity transmission systems are expected to be the backbone of hture multimedia communications. Considerable effort has been devoted to developing ultra-high-speed and ultra-highcapacity transmission systems, such as using wavelength division multiplexing (WDM) and time division multiplexing (TDIM). Recently, a 1.1-Tb/s (%-wavelength X 20 Gb/s) WDlM transmission experiment was reported [ 11. High-speed electronic circuit technology is the key to TDM systems for 4O-Cib/s data rates and WDM systems which use 40-Gb/s data rates per channel.Hletrojunction bipolar transistors (HBTs) have demonstrated excellent potential for high-speed ICs and microwave applications. We have already developed highspeed ICs for lO-Gb/s and 20-Gb/s optical transmission systems using AlGaAdGaAs HBTs with fT of 45 GHz and f, , of 105 GHz and a hetero-gurdring hlly self-aligned HBT (HG-FST) process [2] [3].Tlhis paper describes the performance of a preamplifier for 40-Gb/s optical transmission systems. The main features are as follows. (1) High-performance AlGaAdInGaAs HBTs with p' regrown extrinsic base layers, instead of InP-based HBTs, were implemented into the circuit. (2) An accurate design technique was used. II . FOR BROADBAND PREAMPLIFIERA preamplifier converts current data signals fi-om a photodetector into voltage data signals and amplifies in an optical receiver. A bandwidth of more than 28 GHz (70 YO of the bit rate) is necessary to achieve 40-Gb/s. The relation between the bandwidth of the preamplifier and the device parameters of the implemented transistor is described in this session. The bandwidths of the preamplifier dependence of the base resistance (RB) and the base transit time ( ' I: F) in conventional AlGaAdGaAs HBTs are shown in Fig. 1. The bandwidth mainly depends on the base resistance and the base transit time, and reductions in the base resistance and the base transit time are indispensable for more broadband preamplifiers. However, there is a trade off between the base resistance and the base transit time. AlGaAshGaAs HBTs with p+ regrown extrinsic base layers, which can reduce both the base resistance and the base transit time, have been implemented into the preamplifier. t I I I I I 0 1 2 D e v i a t i o n ( a r b . ) Fig 1 The bandwidths of the preamplifier dependence of the base resistance and the base transit time in a conventiona...

High-gain GaInP/GaAs HBT monolithic transimpedance amplifier for high-speed optoelectronic receivers

“…Very high bandwidths have been reported for receivers fabricated by various technology approaches, such as 23 GHz for a monolithic InF'/InGaAs HBT transimpedance amplifier [ 11 and 20 Gb/s operation speed with a sensitivity of -17.6 dBm at a bit error rate of has been achieved using InP HBT OEICs [2]. A bandwidth of 18.5 GHz has been demonstrated for a monolithic InAlAdInGaAs HEMT photoreceiver [3] while AlGaAdInGaAs preamplifiers showed 40 Gb/s transmission capability with a bandwidth of 34.6 GHz and a transimpedance gain of 41.6 dBQ [4]. The use of InP based technology offers the advantage of integration possibility with PIN photodiodes and thus operation at 1.55 ym wavelength.…”