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The surface-potential-based compact MOS model PSP is reviewed with special emphasis to features of interest to analog and RF designers. Various aspects of the model are discussed, such as Gummel symmetry, capacitance reciprocity at V DS = 0 V, parasitic resistances, junction modeling, distortion modeling, and noise modeling. Examples from circuit design are used to illustrate the benefits of the PSP model.

A computationally efficient physics-based wideband predictive inductor compact model is presented that is capable of evaluating the impact on inductance and quality factor of dummy metal fill-cells. In a modern integrated-circuit process, high amounts of these fill-cells are required to meet metal density rules and guarantee adjacent circuit integrity. The predictions made with this model are shown to be in agreement with data measured on symmetrical octagonal inductors realized in a 90-nm CMOS process with varying amounts of dummy metal fill-cells. We further provide all inductance equations, list additional sources of eddy current losses, and discuss layout modifications, which would further improve the performance of the integrated inductors

A new approach to numerical noise simulation for MOSFETs based on bipolar 2D drift-diffusion and hydrodynamic models is presented, where the hierarchical approach for volume transport has been extended to the case of inversion layers. With the new models RF noise in scaled NMOSFETs is investigated and simulation results are compared to measurements for a 180 nm technology. Important noise quantities like the drain and gate excess noise factors and the gate/drain correlation coefficient are discussed in detail. It is found that the drain excess noise factor increases only moderately in short channel devices down to 70 nm gate length independent of the device type (bulk, SOI or double gate). Although the gate excess noise factor increases significantly at shorter gate lengths, the minimum noise figure strongly decreases predicting superior noise performance for sub-100 nm devices. Furthermore, the impact of the substrate resistance on RF noise is discussed including bias conditions near breakdown, where carrier generation by impact ionization becomes significant.

For the first time, the effects of poly depletion on the RF noise performance of advanced CMOS transistors are reported and analyzed. Based on measurements and physical device simulations we quantify the increasing danger of poly gate depletion with downscaling on the RF noise parameters of CMOS devices. While poly depletion does not affect the minimum noise figure, it results in a degradation of the noise matching freedom for RFIC designers. This trend worsens with technology downscaling.

A new noise-figure measurement method, which combines the simplicity of the "classical" Y-factor method with the accuracy of the widely used "cold noise-source" method, is reported. Implemented in our fully automated wide-band 1-18-GHz on-wafer noise-parameter measurement system, accurate results are obtained using a small set of precharacterized source impedances. We illustrate our method and its accuracy with data taken on a low-noise GaAs pseudomorphic high electron-mobility transistor device, and quantify the impact of the instrumental uncertainties on the extracted noise parameters.

The impedance errors remaining after applying the industry standard "open-short," a "pad-open-short," and a "open-short-load" deembedding scheme on a 0.43-nH 20-GHz high-Q single-loop inductor test structure are investigated using real S-parameter data taken up to 50 GHz. Since the latter two deembedding schemes both correct for all parasitic elements of the test structures, they are, at least in principle, error free. The accuracy of the "open-short-load" deembedding scheme, however, critically depends on how well the reactive part of the load resistance is accounted for. This issue makes the more simple "pad-open-short" deembedding scheme an attractive choice because the required split between external and internal capacitances is easy to make, either based on process and layout information or from measurements done on a "pad" dummy structure

This paper presents a new method, developed for the capacitance–voltage (C–V) characterization of leaky dielectrics. The method comprises measurements in the gigahertz range on specially designed RF test structures. The method is verified against high-frequency C–V measurements on NMOS and PMOS structures. It yields reliable results even when the gate leakage is in excess of 100 A/cm2.

The RF noise in 0.18-/spl mu/m CMOS technology has been measured and modeled. In contrast to some other groups, we find only a moderate enhancement of the drain current noise for short-channel MOSFETs. The gate current noise on the other hand is more significantly enhanced, which is explained by the effects of the gate resistance. The experimental results are modeled with a nonquasi-static RF model, based on channel segmentation, which is capable of predicting both drain and gate current noise accurately. Experimental evidence is shown for two additional noise mechanisms: 1) avalanche noise associated with the avalanche current from drain to bulk and 2) shot noise in the direct-tunneling gate leakage current. Additionally, we show low-frequency noise measurements, which strongly point toward an explanation of the 1/f noise based on carrier trapping, not only in n-channel MOSFETs, but also in p-channel MOSFETs.

The impedance errors remaining after conventional de-embedding for a high-speed transistor and a single-loop inductor test structure are investigated. A new de-embedding strategy using a physics-based lumped-element model for the test-structure parasitics calibrated on the frequency-dependent "open" and "short" dummy impedances is described, which reduces the experimental uncertainty on the de-embedded figures of merit. Using this new "calibrated lumped-element" de-embedding technique, we have been able to increase the "worst-case" values for the quality factor Q of a 0.6-nH 10-GHz single-loop inductor from 15 to 20 and for the f/sub max/ of a high-speed SiGe bipolar transistor from 80 to 110 GHz. The de-embedding technique presented here is of great importance to develop confidence in on-wafer S-parameter measurements taken at ever increasing microwave frequencies.

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.

A new method allowing an automated, polarization resolved, complete characterization of fiber pigtailed semiconductor optical amplifiers is presented and discussed. The method is applied to a high performance, polarization insensitive 1310 nm strained layer multiple-quantum-well semiconductor optical amplifier. For this amplifier 36 dB fiber to fiber gain, a 3 dB gain saturation output power of 15 dBm and a noise figure of 6.5 dB are demonstrated and the polarization dependence of these key performance figures is clarified. The result is presented in a form which should enable the end-user to derive realistic performance figures which will be obtained for a fluctuating random input signal state of polarization.

The performance of inductors realized in various metal layer combinations available in an advanced CMOS process with a mixed copper-aluminum backend is compared. Due to the skin effect, the gain in performance is generally smaller than anticipated from the reduction in dc resistance. We show that beyond a certain frequency, adding an aluminum layer on top of a copper inductor stack actually degrades the inductor performance because the skin resistance of the top metal is enhanced.

Progress in long-wavelength strained (compressive and tensile) InGaAs(P) quantum well semiconductor lasers and amplifiers for applications in optical fibre communication systems is reviewed. By the application of grown-in strain, device performance is considerably improved to such an extent that conventional bulk and unstrained quantum well active-layer devices are outperformed, while high reliability, similar to that of unstrained devices, is maintained.

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.

This paper presents an 8-elements phased array receiver front-end in 45nm CMOS technology. The receiver uses a 4-bit resolution RF phase shifter to compensate for the free-space propagation delay and an active eight-to-one power combiner enabling beam-forming. Each path shows more than 15.8dB of power gain with

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. >

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 novel single-pass single-amplifier polarization-insensitive optical amplifier configuration is proposed and used to solve the inherent polarization sensitivity of a compressively strained multiple-quantum-well (MQW) laser amplifier. The polarization-independent operation is obtained by single-passing the light with the preferred polarization through the amplifier chip. Therefore the light is decomposed into two mutually orthogonal polarizations and sent in opposite directions through the semiconductor laser amplifier. An analysis is presented that shows that the residual gain ripple and polarization sensitivity are sufficiently reduced when the residual facet reflectivities of the traveling-wave semiconductor laser amplifier are in the range below 10/sup /spl minus/4/. >

We report a single-loop inductor suitable for integration in a differential voltage-controlled oscillator (LC-VCO) with 0.6-nH inductance and record quality factors of 18 at 10 GHz and 20 at 15 GHz fabricated in an industrial CMOS process on a 10 /spl Omega/cm substrate. A new lumped element model which accurately describes the inductor performance without the need for frequency-dependent elements is presented. During the course of this work, we found that a patterned ground shield significantly improves the inductor performance at these frequencies, but only when the polysilicon bars are connected from the center of the inductor.

A new, compact expression for the effective FinFET gate resistance is derived and validated on experimental data. Moreover, FinFET thermal noise measurements are presented and analyzed. We show that the observed increase of drain current noise with drain-source voltage is not due to microscopic excess noise, but to the access resistances, which modify the transfer of channel thermal noise to the terminals.

High-quality strained-layer InxGa1-xAs-InP quantum well structures, as revealed by photoluminescence and transmission electron microscopy studies, were grown by low-pressure metalorganic vapour phase epitaxy (MOVPE). Laser diodes at 1.5 μm wavelength employing compressively as well as tensile strained InxGa1-xAs-InGaAsP quantum wells with better performance than the much more extensively studied bulk InGaAsP and unstrained quantum well lasers are demonstrated. Threshold current densities as low as 92 and 147 A/cm2 were measured from tensile and compressively strained single quantum well lasers. For both signs of the strain, 0.8 mA threshold current operation is achieved of all-MOVPE grown semi-insulating planar buried heterostructure (SIPBH) lasers. These data represent, to the best of our knowledge, the lowest values reported so far for 1.5 μm wavelength lasers grown by any technique. Compressively strained multiple quantum well (MQW) lasers are found to excel in high power operation, as demonstrated by the record CW output power of 325 mW, resulting from improved threshold current, temperature sensitivity of the threshold current and external differential efficiency. The tensile strained MQW lasers show very high differential and total gain, resulting in very high operating temperature up to 140°C. Three-section distributed feedback lasers employing a compressively strained InGaAs MQW active region showed very large wavelength tuning ranges as high as 7.2 nm with a minimum linewidth as low as 700 kHz.

In this paper, it is shown that self-heating causes a gigantic effect on the capacitances of MOSFETs/FinFETs. The effect is used to determine the SOI FinFET thermal impedance and to determine the temperature rise during FinFET operation.

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). >

First the surface-potential-based compact MOS model, PSP, is introduced. After a discussion of the general advantages of this model, it is benchmarked against measurements from the 45 nm technology node. Finally, we zoom in on the modeling in PSP of two effects that are of special importance for RF applications: distortion and noise.

Compact modeling is an area that gets more and more mature. Collaborations and standardization efforts have emerged. In this paper we present some special requirements that are important when constructing physics-based compact models. We will substantiate our statements on two recent examples, an inductor model and a MOSFET model.

The physical background of the thermal noise equations of the PSP MOSFET model [1] is presented. The PSP thermal noise model is shown to pass a number of proposed benchmark tests for MOSFET thermal noise. Without any fitting parameters, it is shown to predict with great accuracy a collection of experimental data on three modern CMOS technologies. The impact of device layout on noise properties is discussed and demonstrated experimentally.

A compact high-gain 1310-nm semiconductor optical amplifier (SOA) module incorporating two photodiodes to detect radiation emitted from the two opposite facets of the amplifier chip is reported. By subtracting their signals, a measure of the amplified signal is obtained without the need for optical filtering, Using this, amplified signals can be stabilized within 0.5 dB over a 25-dB range of input signals.

A 1310-nm reflective semiconductor optical amplifier with a gain uncertainty of only 0.8 dB at an average gain level of over 30 dB has been demonstrated using a microoptic polarization reversing retroreflector. For this amplifier 3-dB saturation output powers of up to 10 dBm and a noise figure of 7.5 dB have been obtained. A low gain uncertainty for undefined input signal polarization states and input signal wavelengths (which may vary over several nanometers) is of primary importance in switching applications.

We have optimized 3 key RF devices realized in standard logic 90 nm CMOS technology and report a record performance in terms of n-MOS maximum oscillation frequency f/sub max/ (280 GHz), varactor tuning range and varactor and inductor quality factor.

A 1310-nm gain clamped semiconductor optical amplifier with amplitude modulation CATV-grade linearity at an output power of 8 mW is demonstrated for the first time. The InGaAsP multiquantum-well laser amplifier is equipped with distributed Bragg reflectors at each end to supply the feedback necessary for gain clamping. The TE optical gain of 21.3 dB is measured to be constant within 0.1 dB up to 25-mW signal output power. Electrical signal distortion experiments are presented to demonstrate the linearity of the device.

A practical 1550-nm polarization independent semiconductor optical amplifier configuration employing compressively strained quantum wells and a few commercially available optical components is reported. Crosstalk from counter propagating light, which may easily occur in such a configuration, has been sufficiently suppressed for practical use. For the entire configuration a net fiber-to-fiber gain of 17 dB, a 3-dB saturation output power of 13 dBm and a noise figure of 9 dB have been demonstrated. The polarization dependence was only 0.7 dB. The polarization independent 1550-nm semiconductor optical amplifier reported here is attractive when power consumption and compactness are of major concern and especially for applications involving nonlinear signal processing and switching.

The self-phase modulation coefficient /spl gamma/ of 1310 nm multiple-quantum-well (MQW) semiconductor optical amplifiers has been investigated. It is found to vary from 16/spl times/10/sup 4/ W/sup -1/ m/sup -1/ for low driving conditions to 3/spl times/10/sup 4/ W/sup -1/ m/sup -1/ for high-driving conditions. This implies that the amount of self-phase modulation occurring in the amplifier is between 1.5-10/spl times/ more than that occurring in the optical fiber following the amplifier. The additional self-phase modulation caused by the semiconductor optical amplifier may be used to achieve compensation for fiber dispersion in optical communication systems at significantly lower average power levels. The linewidth enhancement factor /spl alpha//sub H/ was found to increase from a value of 2 at low driving conditions, in agreement with results reported for MQW lasers, to a value of 3 at high-driving conditions.

The noise figure degradation due to saturation by amplified spontaneous emission of high-gain 1310-nm polarization insensitive multiple-quantum-well optical amplifiers has been investigated systematically by studying amplifiers of different lengths. It is found that the intrinsic noise figure of 4 dB of a device with 20-dB single-pass gain is degraded to about 5 dB for a device having 36-dB single-pass gain. This degradation in noise figure is very modest, compared to results reported earlier for semiconductor optical amplifiers with bulk-gain media, illustrating the benefits of using a quantum-well gain medium in semiconductor optical amplifiers.

A highly accurate predictive inductor model for integrated symmetric inductors with center tap and patterned ground shield is presented. This model is based on a modified Greenhouse algorithm where current crowding due to skin and proximity effects is included by considering the spread in parallel sub-loop inductances. This scalable symmetrical inductor equivalent circuit model covers all operating conditions, and yet only requires dimensions and back-end layer thicknesses. We have verified this scalable model for a large number of inductors from three industrial IC processes and found excellent agreement with measured inductances, Q-factors, and resonance frequencies.

Accurate compact modeling of induced gate noise is a prerequisite for RF CMOS circuit design. Existing models underestimate the induced gate noise for short-channel devices. In this paper, a new model is introduced, based on an improved Klaassen-Prins approach, which accurately accounts for velocity saturation. The model accurately describes noise without fitting any additional parameters.

A unidirectional multiple-quantum-well booster amplifier module for the 1310-nm transmission window with a high 3-dB gain saturation output power of 18 dBm and a fiber-to-fiber gain of 17 dB is demonstrated. The module is equipped with a polarization-maintaining input fiber and optical isolators have been included. The booster amplifier was tested with a 1310-nm DFB laser directly modulated at 10 Gb/s, showing that 14.6 dBm of average fiber-launched output power could be obtained at 1 dB BER penalty, and that power budgets of 26.8 dB and 39.4 dB could be realized for a PIN photodiode receiver and an optically preamplified receiver, respectively, making repeaterless 10 Gb/s transmission over 70 to 100 km of standard single-mode optical fiber at 1310 nm a practical option.

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 today's directly modulated linear semiconductor lasers. >

We demonstrate that the quality factors measured on on-wafer (spiral) inductor test-structures are largely influenced by the choice between ground-signal and ground-signal-ground probe configuration. In particular when the SOLT network analyzer calibration technique is used in combination with ground-signal probing, the quality factor value can be overestimated significantly.

We study the the thermal noise of short-channel NMOS transistors in a commercially available 0.13 micron CMOS technology. The experimental results are modeled with a non-quasi-static RF model, based on the principle of channel segmentation. The model is capable of predicting both drain and gate current noise accurately, without fitting any parmeters to the measured noise data. An essential ingredient of the model is the gate resistance, which is shown to dominate the gate current noise. In our optimized device layouts, this gate resistance is mainly determined by the silicide-to-polysilicon contact resistance.

We present an 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.

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.

1.5- mu m wavelength In/sub x/Ga/sub 1-x/As/InGaAsP (x=0.7, resulting in 1.2% compressive strain and x=0.53, resulting in zero strain) multiple quantum well (MQW) structures were grown on

An unidirectional polarization-insensitive multiple quantum well laser amplifier module for the 1300-nm window with a record high gain of 27 dB and a 3-dB saturation output power of 13 dBm is demonstrated. The module gain has a 3-dB width exceeding 60 nm and shows a typical polarization sensitivity and gain ripple as low as 0.3 dB. To provide immunity for backscattered or reflected light, polarization independent optical isolators were inserted in the input and output coupling optics of the package. A practical optical amplifier module for the 1300-nm window is very desirable, because most of the presently installed fiber has its zero dispersion wavelength around 1310 mm, while much of the older fiber often only can be operated around this wavelength. >

The temperature characteristics of a 1300 nm polarization-insensitive multiple quantum well laser amplifer are investigated at a constant level of the amplified spontaneous emission. Upon increasing the amplifier temperature from O/spl deg/C to 40/spl deg/C, a 20% increase in the gain bandwidth and a twofold increase in the saturation output power, due to an increase in Auger recombination, are observed. The implications of these results on the ultimate capacity of cascaded amplifier systems is evaluated using the concept of the maximum length amplifier cascade. When operated at 40/spl deg/C, this length extends to 6000 km, which is of great relevance for the design of 1300 mm soliton systems, because these short pulses are considered to be able to traverse these large lengths of optical fiber without distortion. >

An unrepeatered 89 km 1310 mn 10 Gbit/s transmission experiment has been carried out for the first time employing an SL-MQW DFB laser diode and a high sensitivity optical front end with 1310 nm strained layer MQW optical amplifiers, enabling a total power budget of 35.8 dB. A record receiver sensitivity of -30.3 dBm at 10 Gbit/s @1310 nm has been demonstrated. >

Direct electronic compensation of the inherent amplification nonlinearity of semiconductor laser amplifiers is investigated. It is found that operating the active layer junction from a voltage source, which in theory would hold the carrier density at a constant value, does not remove the amplification nonlinearity because of the intraband carrier dynamics. However, compensation of the nonlinearity is shown to be possible by driving the laser amplifier from a negative output impedance source. Using this at 80 mA drive current compensation of the amplification nonlinearity is demonstrated for a 1310 nm polarization insensitive multiple quantum well laser amplifier showing 18 dB gain (13 dB fiber to fiber) and a nonlinearity of 0.36 dB/mW. It is further shown that the intraband carrier dynamics, mainly the carrier heating, cause limitations to both the driving conditions for which the nonlinearity can be compensated, and to the use of laser amplifiers as an amplifying detector.

We report on the analog performance of gain-clamped semiconductor optical amplifiers (GC-SOAs) with a full 50-550 MHz 77-channel NTSC loading. The optical gain of such an amplifier is linear i.e., independent of input power, when operated under gain-clamped conditions. The amplifier has distributed Bragg reflectors (DBR) at each end, which cause wavelength-selective feedback and hence, laser action at the DBR wavelength. This fixes the carrier concentration, effectively damping the optical gain of the device. The laser light serves as a reservoir of optical power and determines the maximum input power for which the device operates under linear conditions. Once the input level exceeds this limit the gain will no longer be clamped, and the device will exhibit the nonlinearities as observed for conventional SOAs. The gain-clamped amplifier developed for this study has a fiber-to-fiber gain of 21 dB at 1310 nm, and operates at input powers up to -12 dBm.

A prototype 0.5 /spl mu/m CMOS LNA with a noise figure of 2.2 dB and a gain of 16.9 dB at 900 MHz at a power consumption of 1.8 mW is reported. This result, and the noise figures obtained on 0.25 /spl mu/m CMOS, are reproduced by simulations, confirming that RF noise modeling can be accurately performed using our public domain MOS Model 9. Simulations are presented for similar LNAs realized in standard CMOS processes with gate dimensions down to 0.13 /spl mu/m. Provided high Q matching circuitry is used, for the latter gate length a noise figure of only 1.1 dB and 27 dB gain at 1800 MHz, at a minimal power consumption of only 0.2 mW, is predicted.