Linear Region Of Operation Research Articles

Energy-harvesting characteristics of PZT-5A under gunfire shock

The energy-harvesting behaviors of a ring-shaped PZT-5A element exposed to gunfire shock are investigated for military applications such as an in-flight power source for electronic fuze. A laboratory test using a pneumatic shock machine up to 3000 g's and a gunfire test accompanied by the acceleration of 65,000 g's have been performed. The PZT-5A element subjected to gunfire shock has worked in its strong-depolarization region, thereby generating the electric energy whose quantity is about 140.4 times larger than that measured in its linear operation region. The experimental studies on the PZT-5A element under dynamic load have demonstrated three physico-electric characteristics: the dependence of piezoelectric constant on load-rate, the shock-aging of piezoelectric effect, and the dependence of energy-transfer efficiency on the change in normalized impulse.

Linear Current-Mode Active Pixel Sensor

A current mode CMOS active pixel sensor (APS) providing linear light-to-current conversion with inherently low fixed pattern noise (FPN) is presented. The pixel features adjustable-gain current output using a pMOS readout transistor in the linear region of operation. This paper discusses the pixel's design and operation, and presents an analysis of the pixel's temporal noise and FPN. Results for zero and first-order pixel mismatch are presented. The pixel was implemented in a both a 3.3 V 0.35 and a 1.8V 0.18 CMOS process. The 0.35 process pixel had an uncorrected FPN of 1.4%/0.7% with/without column readout mismatch. The 0.18 process pixel had 0.4% FPN after delta-reset sampling (DRS). The pixel size in both processes was 10times10 mum2, with fill factors of 26% and 66%, respectively.

자율주행차량과 로봇의 안내를 위한 자계위치인식시스템

본 논문은 자율주행차량과 로봇의 안내를 위한 새로운 자계위치인식방법을 제안한다. 차량 및 로봇이 자율주행을 하기 위해서는 이동경로상의 현재 위치를 인식하는 것이 기본적으로 요구된다. 자계기반 자율주행차량과 로봇은 자성체로부허 발생되는 자계를 계측하여 위치정보를 검출한다. 이러한 자계위치인식시스템에서 지구자계는 기본적인 왜란으로 작용한다. 본 논문에서는 지구자계의 영향을 제거하기 위해 다수의 1축 자계센서 열을 구성하였으며, 자계센서 출력의 선형동작영역을 이용하여 정밀한 위치인식시스템을 개발하였다. 제안하는 방법이 자율주행차랑과 로봇의 안내를 위해 사용 가능함을 실험을 통하여 검증하였다. In this paper, a new magnetic position sensing mettled for autonomous vehicle and robot guidance is presented. In autonomous vehicle and robot control, position sensing is an important task for the identification of their locations, such as the current position within a trajectory. The magnet based autonomous vehicle and robot was identified position via magnetic materials. In the magnetic sensing system, the Earth field is one of the largest disturbance. To removal of the Earth field, this paper proposes 1-dimensional magnetic field sensors array and develops precise petition sensing system using linear operating region of the magnetic field sensor. This proposal is verified a feasible magnetic position sensing system for autonomous vehicle and robot guidance by the experimental results.

A photo-dependent capacitance model of GaAs MESFET's

A new and simple analytical model for determining the photo-effects on the gate–source and gate–drain capacitances of GaAs MESFET's has been presented for both the linear and saturation regions. A new model for the photovoltage developed across the Schottky junction due to the illumination has been used to investigate the photo-dependent characteristics of the above capacitances. It has been observed that the gate–source and gate–drain capacitances are increased with the increase in the incident illumination level to the device in its linear region of operation whereas in the saturation region, the gate–source capacitance is increased but the gate–drain capacitance is observed to be decreased with the increase in the incident optical intensity level. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Closed-loop identification of wafer temperature dynamics in a rapid thermal process

Single wafer rapid thermal processing (RTP) can be used for various wafer fabrication steps such as annealing, oxidation and chemical vapor deposition. A key issue in RTP is accurate temperature control, i.e., the wafer temperatures should be rapidly increased while maintaining uniformity of the temperature profile. A closed-loop identification method that suppresses RTP drift effects and maintains a linear operating region during identification tests is proposed. A simple graphical identification method that can be implemented on a field controller for autotuning and a nonlinear least squares method have been investigated. Both methods are tested with RTP equipment based on a design developed by Texas Instruments.

채널구조와 바이어스 조건에 따른 Si0.8Ge0.2pMOSFET의 저주파잡음 특성

High performance <TEX>$Si_{0.8}Ge_{0.2}$</TEX> heterostructure metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated using well-controlled delta-doping of boron and <TEX>$Si_{0.8}Ge_{0.2}$</TEX>/Si heterostructure epitaxal layers grown by reduced pressure chemical vapor deposition. In this paper, we report 1/f noise characteristics of the SiGe pMOSFETs measured under various bias conditions of the gate and drain voltages changing in linear operation regions. From the noise spectral density, we found that the gate and drain voltage dependence of the noise represented same features, as usually scaled with <TEX>$f^{-1}$</TEX> However, 1/f noise was found to be much lower in the device with boron delta-doped layer, by a factor of <TEX>$10^{-1}_10^{-2}$</TEX> in comparison with the device fabricated without delta-doped layer. 1/f noise property of delta-doped device looks important because the device may replace bipolar transistors most commonly embedded in high-frequency oscillator circuits.

Steady-state analyses for reactive distillation control: An MTBE case study

Abstract An approach, based purely on steady-state analyses, for synthesizing effective control structures for reactive distillation (RD) columns is presented. The main idea is to analyze the steady-state relationships between the manipulated (input) variables and the potential controlled (output) variables to identify input–output (IO) pairings that are sensitive and avoid steady-state multiplicities providing a large range of nearly linear operating region around the base case design. Traditional SISO control loops are then implemented using these IO pairings to obtain control structures that maintain the column near the design product purity and conversion for the anticipated primary disturbances. The Niederlinski Index is used to eliminate dynamically unstable pairings in control structures with multiple loops. The approach is demonstrated on an example MTBE RD column. The impact of steady-state multiplicities on control structure design is highlighted.

Consistent Noise Models for Analysis and Design of CMOS Circuits

Simple, physics-based MOSFET noise models, valid over the linear, saturation, and subthreshold operation regions are presented. The consistency of the models representing series-parallel associations of transistors is verified. Simple formulas for hand analysis using the inversion level concept are developed. The proportionality between the flicker noise corner frequency and the transistor transition frequency is proved and experimentally verified under wide bias conditions. Application of the noise models to a low-noise design is shown.

High-frequency harmonic distortion in feedback amplifiers: analysis and applications

An approach for the evaluation of high-frequency harmonic-distortion factors in feedback systems is proposed and the results obtained are applied to feedback amplifiers. Under the assumption that transistors are not driven out of their linear operating regions, small-signal analysis and conventional algebra are exploited to derive understandable and compact expressions highly improving the comprehension of harmonic-distortion generation. The impact of the frequency compensation utilized (namely, dominant-pole or Miller technique) on linearity performance is evaluated and the high-frequency distortion properties of closed-loop single-stage and two-stage amplifiers are analyzed and compared. The accuracy of the analysis, also in view of the given applications, is confirmed through extensive simulations with Spectre on idealized models as well as on CMOS transistor-level circuits. Despite the approximated nature of the analytical models, predicted data are found in very close agreement with simulations in nearly all the frequency range of interest.

An improved physics-based 1/ f noise model for deep sub-micron MOSFETs

1/ f noise has been investigated on the drain to source voltage of deep sub-micron p-channel MOSFETs, with 5 μm channel width and 0.32–1.2 μm varying lengths. The MOSFETs were fabricated using 0.18 μm medium doped drain technology. The measurements were performed in strong inversion and linear operation region at room temperature. Noise parameters for BSIM3 simulation were extracted from the 1/ f noise measurements. The oxide trap densities calculated from these noise parameters, however, showed a significant difference from transistor to transistor on the same die. Moreover, the drain voltage power spectral density exhibited a stronger dependence on channel length than the 1/ L dependence expected from BSIM3 model. A modified BSIM3 model has been developed, based on threshold voltage variation along the channel. The modified model provides a good quantitative agreement with the noise power spectral density as a function of gate voltage. In addition, the modified flicker noise model more accurately predicts the oxide trap density. Carrier scattering coefficient was also obtained from the noise fitting parameters.

Back-gate and series resistance effects in LDMOSFETs on SOI

Detailed experimental results are used to develop a new model for the linear region of operation of lateral DMOSFETs (LDMOSFETs) on silicon-on-insulator (SOI) that includes the influence of the buried oxide and back-gate. Back-gate biasing results in double-channel conduction and bias-dependent series resistance. Pertinent techniques for parameter extraction are presented and contrasted to those currently used in low-voltage SOI MOSFETs. The typical feature of LDMOSFETs is the significant change in series resistance as the back-gate is driven from accumulation to inversion. The model allows a clear identification of the architectural and technological parameters of the device.

Validation of bulk-charge effect parameter extraction in MOSFETs

Our recently proposed method to extract the bulk-charge effect parameter in MOSFETs is scrutinized by studying SOI devices, a-Si:H TFTs and short- as well as long-channel bulk MOSFETs. The method requires measuring the drain current as a function of gate voltage at two small values of drain voltage chosen in the linear region of operation.

Low-frequency noise in near-fully-depleted TFSOI MOSFETs

Low-frequency (1/f) noise in near-fully-depleted Thin-Film Silicon-On-Insulator (TFSOI) CMOS transistors designed for sub-l-V applications is investigated in the subthreshold region, linear region, and saturation region of operation for the first time. The noise in these surface-channel devices is composed of a bias invariant 1/f component and a bias dependent generation-recombination (G/R) component that becomes enhanced in the subthreshold region of operation for both n- and p-channel MOSFETs. Results presented in this letter are consistent with the noise being dominated by a number fluctuation model. These results demonstrate that the bias independent 1/f noise spectrum of the n-channel TFSOI MOSFET is comparable to the 1/f noise level found in conventional bulk silicon submicron CMOS fabrication processes.

A ±1.5-V, 4-MHz CMOS continuous-time filter with a single-integrator based tuning

A 4-MHz, fifth-order elliptic low-pass Gm-C filter is described whose characteristics are tuned by an on-chip automatic tuning circuit. The tuning circuit uses only one integrator as the master of tuning instead of problematic voltage controlled oscillator (VCO) and voltage controlled filter (VCF). MOS transistors in linear operation region perform the voltage-to-current conversion in an operational transconductance amplifier, and thereby we achieved /spl plusmn/1.5 V operation. A prototype filter was implemented in a 0.8-/spl mu/m double-poly, double-metal CMOS process. The filter exhibits the dynamic range of 57.6 dB and dissipates 10 mW with /spl plusmn/1.5-V supply. The stopband attenuation is better than 45.0 dB and the passband ripple is smaller than 1.0 dB.

Operation of a voltage source converter at increased utility voltage

The operation of a voltage source converter (VSC) with regeneration capability, controllable power factor, and low distortion of utility currents is analyzed at increased utility voltage. Increase in the utility voltage causes a VSC to saturate and enter a nonlinear mode of operation. To operate under elevated utility, two steps are taken: (1) a pulse width modulation (PWM) algorithm is implemented which extends the linear region of operation by 15%, and (2) a PWM saturation regulator is used to control the reactive current at higher utility voltages. The PWM algorithm reduces the switching losses by at least 33% and the effect of blanking time by one-third. All analytical results are experimentally verified on a 100 kW three-phase VSC.

Control Sensor Linearization Using Artificial Neural Networks

Traditionally, the issues of cost, size, and weight of artificial neural network implementations have not been the primary concern of researchers. These issues are important in many applications such as those required in space travel, high-volume commercial products, or products with size limitations. In this paper, we discuss methods to improve the characteristics of control sensors using compact and low-cost circuitry. Our objective is to extend the linear region of operation of a nonlinear sensor using artificial neural networks. An analog circuit approach was investigated for high-speed applications and a microcontroller approach for low-speed applications. The methods are applied to the design of a discrete-component phase-locked loop. Both approaches resulted in doubling the sensor‘s linear range.

Linear behavior of a near-field optical scanning system

A hybrid finite-difference time-domain and angular-spectrum propagation modeling technique is used to study the imaging properties of a near-field optical scanning system with dielectric samples. The model is used to calculate system transfer functions based on scanning sinusoidal gratings of various spatial periods or on scanning a straight edge and then taking a derivative and a Fourier transform. Results from these two methods are in good agreement. A square-wave grating is simulated by linear addition of component sine-wave grating images that are weighted by the transfer function. The image generated by this method agrees well with an image generated by direct use of the hybrid model. In the region of parameter space investigated with the model, the near-field optical scanning system exhibits nearly linear behavior. The region of linear operation depends on the index of the sample and on the probe-to-sample spacing.

Pump statistics and field squeezing in the extended Jaynes-Cummings model for a many m-photon CEL

I extend the Jaynes-Cummings model for a many m -photon CEL recently obtained to a more general situation in which the upper atomic level is extended to m +1 almost degenerate levels, the ( n+m )-level atom interacts with a field via ( m +1)( n −1) m -photon processes. Based on the J-C model, and taking the pump statistics into consideration, we show that the photon number-squeezing of the many one-photon CEL also exists in the linear region of laser operation, and the squeezing increases with increasing upper atomic levels.

Pump statistics and field squeezing in the extended Jaynes-Cummings model for a many m-photon CEL

I extend the Jaynes-Cummings model for a many m-photon CEL recently obtained to a more general situation in which the upper atomic level is extended to m+1 almost degenerate levels, the ( n+m)-level atom interacts with a field via ( m+1)( n−1) m-photon processes. Based on the J-C model, and taking the pump statistics into consideration, we show that the photon number-squeezing of the many one-photon CEL also exists in the linear region of laser operation, and the squeezing increases with increasing upper atomic levels.

A GaAs Power MESFET Operating at 3.3V Drain Voltage for Digital Hand-Held Phone

A GaAs power metal semiconductor field effect transistor (MESFET) operating at a voltage as low as 3.3V has been developed with the best performance for digital hand-held phone. The device has been fabricated on an epitaxial layer with a low-high doped structure grown by molecular beam epitaxy. The MESFET, fabricated using 0.8 μm design rule, showed a maximum drain current density of 330 mA/mm at Vgs = 0.5V and a gate-to-drain breakdown voltage of 28 V. The MESFET tested at a 3.3 V drain bias and a 900 MHz operation frequency displayed an output power of 32.5-dBm and a power added efficiency of 68%. The associate power gain at 20 dBm input power and the linear gain were 12.5dB and 16.5dB, respectively. Two tone testing measured at 900.00MHz and 900.03MHz showed that a third-order intercept point is 49.5 dBm. The power MESFET developed in this work is expected to be useful as a power amplifying device for digital hand-held phone because the high linear gain can deliver a high power added efficiency in the linear operation region of output power and the high third-order intercept point can reduce the third-order intermodulation.