L.F. Tiemeijer

RF-CMOS performance trends

The impact of scaling on the analog performance of MOS devices at RF frequencies was studied. Trends in the RF performance of nominal gate length NMOS devices from 350-nm to 50-nm CMOS technologies are presented. Both experimental data and circuit simulations with an advanced validated compact model (MOS Model 11) have been used to evaluate the RF performance. RF performance metrics such as the cutoff frequency, maximum oscillation frequency, power gain, noise figure, linearity, and 1/f noise were included in the analysis. The focus of the study was on gate and drain bias conditions relevant for RF circuit design. A scaling methodology for RF-CMOS based on limited linearity degradation is proposed.

High-performance 1.5 mu m wavelength InGaAs-InGaAsP strained quantum well lasers and amplifiers

Improved performance of 1.5- mu m wavelength lasers and laser amplifiers using strained In/sub x/Ga/sub 1-x/As-InGaAsP quantum well devices is reported. The device structures fabricated to study the effects of strained quantum wells on their performance are described. These devices showed TM mode gain, demonstrating the strain-induced heavy-hole-light hole reversal in the valence band. Lasers using these tensile strained quantum wells show higher and narrower gain spectra and laser amplifiers have a higher differential gain compared to compressively strained quantum well devices. Consequently, the tensile strained quantum well lasers show the smallest linewidth enhancement factor alpha =1.5 (compression alpha =2.5) and the lowest K-factor of 0.22 ns (compression K=0.58 ns), resulting in an estimated intrinsic 3 dB modulation bandwidth of 40 GHz (compression 15 GHz). >

Progress in long-wavelength strained-layer InGaAs(P) quantum-well semiconductor lasers and amplifiers

The progress in long-wavelength compressively and tensile-strained InGaAs(P) quantum-well semiconductor lasers and amplifiers is reviewed. By the application of grown-in strain, the device performance is considerably improved such that conventional bulk and unstrained quantum-well active-layer devices are outperformed, while a high reliability is maintained. >

Polarization insensitive multiple quantum well laser amplifiers for the 1300 nm window

A polarization insensitive (less than 1 dB gain difference over the 3 dB gain bandwidth) multiple quantum well laser amplifier for the 1300 nm window is reported for the first time. The amplifiers employ a single active layer containing three tensile strained and four compressively strained quantum wells and show a fiber to fiber gain of 16 dB at 1310 nm and 200 mA driving current. Furthermore at the same wavelength these devices have a record low fiber coupled noise figure of 6.5 dB and a conveniently high fiber coupled saturation output power of 13 dBm for both polarizations.

Accurate thermal noise model for deep-submicron CMOS

Extensive measurements of drain current thermal noise are presented for 3 different CMOS technologies and for gate lengths ranging from 2 /spl mu/m down to 0.17 /spl mu/m. Using a surface-potential-based compact MOS model with improved descriptions of carrier mobility and velocity saturation, all the experimental results can be described accurately without invoking carrier heating effects or introducing additional parameters.

RF capacitance-voltage characterization of MOSFETs with high leakage dielectrics

We present a MOS Capacitance-Voltage measurement methodology that, contrary to present methods, is highly robust against gate leakage current densities up to 1000 A/cm/sup 2/. The methodology features specially designed RF test structures and RF measurement frequencies. It allows MOS parameter extraction in the full range of accumulation, depletion, and inversion.

Reduced intermodulation distortion in 1300 nm gain-clamped MQW laser amplifiers

A 1300 nm gain-clamped DFB multiple quantum well laser amplifier with negligible pass band ripple, 20 dB fiber to fiber gain, and 10 dB reduction in gain saturation is demonstrated. The remaining gain saturation is attributed to longitudinal hole burning. After some modifications the reduction in gain saturation is improved to more than 30 dB for an input signal having the same polarization state as the lasing mode. From these experiments and a theoretical analysis it is concluded that there is a potential for realizing highly linear 1300 nm CATV semiconductor laser amplifiers using gain-clamping with less intermodulation distortion than todays directly modulated linear semiconductor lasers.<<ETX>>

RF-distortion in deep-submicron CMOS technologies

The distortion behaviour of MOSFETs is important for RF-applications. In this paper the influence of technology variations (oxide thickness, substrate doping,...) on distortion is investigated using measurements and a recently developed compact MOSFET model. The influence on distortion of technology scaling down to 0.18 /spl mu/m is verified and further scaling according to the ITRS-roadmap is predicted.

High-performance /spl lambda/=1.3 /spl mu/m InGaAsP-InP strained-layer quantum well lasers

Compressively and tensile strained InGaAsP-InP MQW Fabry-Perot and distributed feedback lasers emitting at 1.3-/spl mu/m wavelength are reported. For both signs of the strain, improved device performance over bulk InGaAsP and lattice-matched InGaAsP-InP MQW lasers was observed. Tensile strained MQW lasers show TM polarized emission, and with one facet high reflectivity (HR) coated the threshold currents are 6.4 and 12 mA at 20 and 60/spl deg/C, respectively. At 100/spl deg/C, over 20-mW output power is obtained from 250-/spl mu/m-cavity length lasers, and HR-coated lasers show minimum thresholds as low as 6.8 mA. Compressively strained InGaAsP-InP MQW lasers show improved differential efficiencies, CW threshold currents as low as 1.3 and 2.5 mA for HR-coated single- and multiple quantum well active layers, respectively, and record CW output powers as high as 380 mW for HR-AR coated devices. For both signs of the strain, strain-compensation applied by oppositely strained barrier and separate confinement layers, results in higher intensity, narrower-linewidth photoluminescence emissions, and reduced threshold currents. Furthermore, the strain compensation is shown to be effective for improving the reliability of strained MQW structures with the quantum wells grown near the critical thickness. Linewidth enhancement factors as low as 2 at the lasing wavelength were measured for both types of strain. Distributed feedback lasers employing either compressively or tensile strained InGaAsP-InP MQW active layers both emit single-mode output powers of over 80 mW and show narrow linewidths of 500 kHz. >

A large signal non-quasi-static MOS model for RF circuit simulation

A large-signal non-quasi-static (NQS) model for RF CMOS circuit simulation is presented that can be built from channel segments described by conventional QS models like BSIM3 or MOS Model 9. This large-signal NQS model is shown to give a very accurate prediction of the high-frequency behaviour of the intrinsic transconductance, the power gain and input resistance.