R.M. Bertenburg

Ultrafast monolithically integrated InP-based photoreceiver: OEIC-design, fabrication, and system application

An InP-based photoreceiver OEIC for /spl lambda/=1.55 /spl mu/m with a bandwidth of 27 GHz is reported. The receiver design, fabrication and characterization is presented. The device consists of an optical waveguide-fed pin-photodiode and a coplanar traveling-wave amplifier being composed of four GaInAs-AlInAs-InP-HEMTs. The photodiode exhibits an external quantum efficiency of 30% and a 3-dB power bandwidth of 35 GHz. HEMTs with 0.7-/spl mu/m gate length, integrated on semi-insulating optical waveguide layers show cutoff frequencies f/sub T//f/sub max/ of 37/100 GHz at zero gate bias. Traveling-wave amplifiers with 0.5-/spl mu/m gate HEMTs have 28-GHz bandwidth. The receiver OEIC is packaged into a module with fiber pigtail and operates successfully within an SDH based 20-Gb/s transmission system. An overall system sensitivity of -30.5 dBm was achieved at a BER=10/sup -9/ after signal transmission over 198-km dispersion shifted fiber.

Development of a low-impedance traveling wave amplifier based on InAlAs/InGaAs/InP-HFET for 20 Gb/s optoelectronic receivers

The applicability of the transimpedance amplifier for optoelectronic receivers becomes doubtful for bit rates higher than 20 Gb/s. So recently the traveling wave amplifier (TWA) concept for high bit rate receiver systems is of increasing interest because it is the preferred amplifier concept for broadband applications like hierarchically organized communication interlinks. TWAs usually are designed with an input and output impedance of 50 /spl Omega/. Thus a main problem of the TWA-concept for an optoelectronic receiver is matching the photo-detector (PD) and the TWA input and reach the requested input RC-bandwidth. The conventional approach is a TWA with an additional 50 /spl Omega/ match resistor at the input line, which has to be integrated directly into the PD itself in order to avoid parasitics. The aim of this paper is to present an alternative concept to the match resistor realized by a TWA with a low-impedance input (25 /spl Omega/), which yields significantly reduced design and fabrication efforts. All simulations for the investigated and optimized designs of the TWA in coplanar technique have been carried out using a commercially available software. For exact noise and sensitivity simulations, an extended temperature noise model (TNM) for heterostructure field-effect transistors was developed and implemented. Finally a comparison with measurement results of the realized TWA is presented.

27 GHz bandwidth integrated photoreceiver comprising a waveguide fed photodiode and a GaInAs/AlInAs-HEMT based travelling wave amplifier

Optical front-ends are considered to play a major role in future communication systems operating at bit rates of 20 or even 40 Gbit/s, as well as in mobile communication systems with fibre-optic distribution networks. Consequently, different approaches for the monolithic integration of high-speed receivers for a wavelength of 1.55 /spl mu/m can be found in the literature. In this paper, we report on the first monolithical integration of an optical receiver OEIC, which combines the advantageous high-speed characteristics of the waveguide integrated pin photodiode and of the travelling wave amplifier (TWA) circuit, both based on the InP material system.

On the applicability of the transimpedance amplifier concept for 40 Gb/s optoelectronic receivers based on InAlAs/InGaAs heterostructure field effect transistors

We examine the design considerations and include a general discussion of the applicability of the transimpedance amplifier concept for optoelectronic receivers at extremely high bit rates up to 40 Gb/s. The receiver design is based on a low gate-leakage InAlAs-InGaAs-InP heterostructure field effect transistor (HFET). The noise modeling of these devices is done using an extended temperature noise model in order to produce a reliable extrapolation far beyond the frequency limits of common measurement setups. The fitted transistor model shows excellent agreement with measured data concerning RF as well as the noise performance. The evidence of inductive peaking near the corner frequency of the transimpedance Z_/sub T/ is correlated to a phase difference between the voltage gain V_/sub u/ and Z_/sub T/ itself. Furthermore, the distinct influence of the length of the feedback line on the receiver performance is discussed. Based on 0.7 /spl mu/m gate HFETs produced by optical lithography and offering a current gain cut off frequency of f/sub T/=40 GHz the following receiver features can be predicted: low frequency transimpedance Z_/sub T0/=39.4 dB/spl Omega/, corner frequency f/sub 3dB/=22 GHz, mean equivalent input noise current density i~/sub na//spl ap/43 pA//spl radic/Hz. Thus the receiver shows an excellent calculated sensitivity of /spl eta/P/sub min/=-13.2 dBm at 40 Gb/s.

10 Gb/s low-noise transimpedance amplifier for optoelectronic receivers based on InAlAs/InGaAs/InP HEMTs

A transimpedance amplifier based on 0.7 /spl mu/m InAlAs/InGaAs/InP HEMTs and applicable for bit rates in the range of 2.5-10 Gb/s has been developed and realized. Compact chip layout guarantees extremely flat gain, linear phase and very small group delay time variations, respectively. Measured transimpedance is Z/sub TO/=51.6 dB/spl Omega/ (f/sub 3/ /sub dB/=8.5 GHz) for the 10 Gb/s version. Mean equivalent input noise current density is i/sub na/=7.98 pA//spl radic/(Hz) over the bandwidth 0/spl les/f/spl les/10 GHz. Calculated receiver sensitivity is /spl eta/P/sub min/=-24.1 dBm@10 Gb/s and BER=10/sup -9/.

On the advantages of InAlAs/InGaAs/InP dual-gate-HFETs in comparison to conventional single-gate-HFETs

Demonstrates that using a Dual-Gate-HFET (DGHFET) as a cascode instead of a conventional InAlAs/lnGaAs Single-Gate HFET (SGHFET) impact ionization itself can be prevented without degradation of the DC- and RF-performance of the device, and consequently, the gate leakage current can be significantly reduced. A direct comparison between both, the DGHFET and the SGHFET, will precisely point out the advantages of a DGHFET compared to a SGHFET in the InAlAs/InGaAs system.