Limitations of Microwave and Millimeter-Wave Mixers Due to Excess Noise

Previous analytical work on microwave and millimeter-wave mixers concentrated on circuit aspects, utilizing for the analysis a simple noise model consisting of shot and thermal noise sources at a constant temperature. However, measurements show that the excess noise created in the diode by hot electrons, intervalley scattering, and traps at the metal-semiconductor interface can be important, especially in millimeter-wave mixers. In this paper, the method of calculation of mixer noise performance in the presence of excess noise is given and its influence discussed for room-temperature, as well as for cooled, mixers.     

Effect of Schottky barrier alteration on the low-frequency noise ofInP-based HEMTs

For the first time the effect of increasing the Schottky barrier's Al content of InP-based InAlAs-InGaAs HEMTs from 48 to 60% on the low-frequency (LF) drain and gate current noise is investigated. It is shown that the LF gate current noise S_IG(f) for the 60% case decreases by almost three decades, while the LF drain current noise S _IDS(f) stays at the same level. From small coherence values, it can be concluded that drain and gate noise sources can be treated separately which facilitates the LF noise modeling of these HEMTs     

基于低频噪声检测的光耦器件可靠性频域筛选新方法

针对光耦器件的可靠性筛选,本文提出全频段阈值筛选方法检测光耦器件内部低频噪声。根据光耦器件内部的低频噪声完成光耦器件可靠性的筛选。实验中利用光耦器件测试系统检测200只光耦器件内部的低频噪声,计算这200只光耦器件全频段平均噪声谱,确定筛选阈值,再根据光耦器件可靠性分类标准,判断被测器件可靠性等级。     

Physical noise modeling of SOI MOSFETs with analysis of theLorentzian component in the low-frequency noise spectrum

The implementation of a general physics-based compact model for noise in silicon-on-insulator (SOI) MOSFETs is described. Good agreement is shown between model-predicted and measured low-frequency (LF) noise spectra. In particular, the behavior of an excess Lorentzian component that dominates the LF noise spectra of SOI MOSFETs is investigated. Shot noise associated with the generation and removal (via recombination or a body contact) of body charge is shown to underlie the behavior of the Lorentzian in both floating-body and body-tied-to-source SOI MOSFET's operating under partially depleted or “mildly” fully depleted conditions; the Lorentzian is suppressed when the body is “strongly” fully depleted. Good physical insight distinguishes the behavior of the Lorentzian components in all these devices, and predicts the occurrence of additional excess noise sources in future scaled technologies. Simple analytic expressions that approximate the full model are derived to provide the insight     

FET noise sources and their effects on amplifier performance at low frequencies

In this brief review paper analytical results concerning the low-frequency (LF) amplifier noise performance of FET's are presented. The effects of interaction between the device basic noise sources, the small-signal model parameters, and the signal source admittance parameters are clearly indicated. The noise performance is found to be essentially determined by the effective surface-state density and the gate insulator thickness product (N_{ss}t_{ox}) in the case of MOSFET's, whereas in the case of JFET's, this is determined by the bulk density of impurity and/or defect generation-recombination (g-r) centers within the depletion region and the half-channel height squared product (N_{TT}a^{2}). Although an increase in the gate electrode area can reduce the equivalent gate noise resistance, this does not improve the noise performance of the device. Quantitative results based on typical device parameters are graphically presented with proper indications as to the upper limit of the LF range, the excess minimum noise figure, and the frequency range within which the noise figure remains below 3 dB level for specified source resistance values. The effects of gate leakage current on the noise performance of JFET's are included in these results.     

Quantum-noise theory for terahertz hot electron bolometer mixers

In this paper, we first review general quantum mechanical limits on the sensitivity of heterodyne receivers. The main aim of the paper is to explore the quantum-noise (QN) properties of hot electron bolometric (HEB) mixers. HEB mixers have a characteristic feature not found in other mixers: based on the "hot-spot" model, the conversion loss varies along the length dimension of the bolometer, and some sections of the bolometer are essentially passive, in which little frequency conversion occurs. We analyze a quantitative distributed quantum-noise model of the HEB mixer, making use of simulated hot-spot model data, that takes into account the continuous variation of the sensitivity along the bolometer bridge. An expression for the HEB receiver noise temperature, including optical input loss, is derived. We find that the predicted double-sideband receiver noise temperature agrees well with the available measured data (up to 5.3 THz). The results of our analysis suggest that QN and classical HEB noise contribute about equally at 3 THz, while at higher terahertz frequencies QN dominates. QN thus appears to show measurable effects in existing HEB mixers and will be even more important to take into account as HEB mixers continue to be developed for higher terahertz frequencies.     

Electrical noise and RTS fluctuations in advanced CMOS devices

A brief overview of recent issues concerning the low frequency (LF) noise in modern CMOS devices is given. The approaches such as the carrier number and the Hooge mobility fluctuations used for the analysis of the noise sources are presented and illustrated through experimental results obtained on advanced CMOS generations. The use of the LF noise measurements as a characterization tool of large area MOS devices is also discussed. The main physical features of random telegraph signals (RTSs) observed in small area MOS transistors are reviewed. The impact of scaling on the LF noise and RTS fluctuations in CMOS silicon devices is also addressed. Experimental results obtained on 0.18 μm CMOS technologies are used to predicting the trends for the noise figure of foregoing CMOS technologies e.g. 0.1 μm and beyond. The formulation of the thermal noise underlying the LF fluctuations in MOSFETs is recalled for completeness.     

基于MATLAB的VLF/LF通信系统仿真

由于大气无线电噪声所涉及的现象非常复杂,观测结果又具有局限性,所以它对VLF／LF(甚低频／低频)通信系统性能影响的理论分析比较困难。本文运用MATLAB提供的Simulink动态仿真平台对大气噪声环境下的VLF／LF通信系统误码性能进行了仿真研究,并结合实例给出了系统的仿真结果,验证了该仿真系统的可行性。     

Impact of advanced processing modules on the low-frequency noise performance of deep-submicron CMOS technologies

Fundamental studies related to the low-frequency (LF) noise performance in semiconductors started more than 40 years ago. In 1957, McWhorter published the first model for the 1/f noise in semiconductors, which is still in use. Whereas for many decades LF noise studies were mainly of fundamental and theoretical interests, in recent years, LF noise characterisation has become a very valuable diagnostic technique for the development of semiconductor materials and devices. Especially, the use of noise characterisation as a tool for reliability predictions has triggered the semiconductor engineering society. Not only the silicon starting material, but also many of the used process modules have a strong impact on the noise performance. This trend is becoming even more pronounced for the advanced deep-submicron technologies. For analog applications of scaled technologies, LF noise may even act as a showstopper. This review, therefore, focuses on the impact of advanced processing on the low-frequency noise behaviour. Both front- and back-end process modules are discussed.     

Technology related design of monolithic millimeter-wave Schottkydiode mixers

The development of monolithic millimeter-wave Schottky diode mixers based on technological parameters is described. The complete equivalent circuit of the monolithic Schottky diode is calculated taking into account the semiconductor layer structure and the device geometry. This model has been used in a harmonic balanced software for designing monolithic single balanced mixers. In V-band a minimum DSB noise figure of 3.3 dB and a minimum conversion loss of 6 dB have been achieved. In W-band a minimum DSB noise figure of 4 dB and a minimum conversion loss of 7 dB have been obtained     

Temporal Noise Analysis and Reduction Method in CMOS Image Sensor Readout Circuit

Temporal noise such as thermal and low-frequency noise (LF noise) in the CMOS imager readout circuit has been analyzed. In addition, the effect of correlated double sampling operation on the noise was included. We have derived an analytical noise equation for the specified readout circuit, and confirmed its validity by comparing it with the simulation result. Thermal noise model which is accurate in short-channel devices operating in saturation region was used. Since the in-pixel devices (source follower and selection transistor) of the readout circuit are relatively small in size, and thus exhibits random telegraph signal (RTS) noise, both 1/f and RTS noise were considered for their LF noise. Based on the analyzed noise components, we presented the noise reduction method by adjusting the transistors sizes in the readout circuit.     

Local-Oscillator Noise Cancellation in the Subharmonically Pumped Down-Converter (Short Papers)

The noise power at the IF output of a superheterodyne mixer which is caused by local-oscillator noise can be significantly reduced by using the recently developed subharmonically pumped down-converter. In many cases this reduction is so large that even noisy sources, such as IMPATT oscillators, can be used to pump low-noise mixers without causing significant degradation of noise figure.     

Analysis and Optimization of Noise in Bipolar RF Harmonic Mixers

A noise analysis of bipolar harmonic mixers (BHM) used for direct-conversion receivers is presented in this paper. Analytical and simulated results for the transfer function of the mixer are presented. Simple analytical expressions describing noise contribution from all sources are derived. Estimation of flicker noise quite agrees with harmonic-balance simulation results. Based on the derived expressions, total time average noise power spectral density (PSD) at the output is compared with simulation results. For the recommended regions of operation, error is less than 20%. The overall BHM noise figure (NF) is calculated and optimized based on a simple extracted formula. Errors introduced by analysis remain within a 1.5-dB margin with respect to simulation results. The validity of analysis for high frequencies is justified. The effect of flicker noise coefficient on the overall mixer NF is compared for different available processes.     

Comprehensive study on low-frequency noise characteristics insurface channel SOI CMOSFETs and device design optimization for RF ICs

Low-frequency (LF) noise, a key figure-of-merit to evaluate device technology for RF systems on a chip, is a significant obstacle for CMOS technology, especially for partially depleted (PD) silicon-on-insulator (SOI) CMOS due to the well-known kink-induced noise overshoot. While the dc kink effect can be suppressed by either using body contact technologies or shifting toward fully depleted (FD) operation, the noise overshoot phenomena still resides at high frequency for either FD SOI or poor body-tied (BT) SOI CMOSFETs. In this paper, floating body-induced excess noise in SOI CMOS technology is addressed, including the impact from floating body effect, pre-dc kink operation, and gate overdrive, followed by the proposal of a universal LF excess noise model. As the physical mechanism behind excess noise is identified, this paper concludes with the suggestion of a device design methodology to optimize LF noise in SOI CMOSFET technology     

Detailed investigation of active CMOS mixers noise in submicron technology

A unified noise figure expression incorporating the thermal noise and flicker noise has been proposed for active CMOS mixers. Based on the derived conversion functions with output resistance effect, the noise transforming factors for different stages are numerically computed to rigorously describe the noise output. The subthreshold conductance has also been taken into account by utilizing the latest continuous noise model and the simplified MOSFET I-V model. As a result, the frequency-dependent characteristic of noise expression is of competency for explaining the flicker noise mechanism, thus can be directly applied to active CMOS mixers with any IF characteristics. And good agreement is obtained between simulations and measurements.     

General noise analysis of nonlinear microwave circuits by thepiecewise harmonic-balance technique

This paper presents a self-consistent set of algorithms for the numerical computation of noise effects in forced and autonomous nonlinear microwave circuits. The analysis relies upon the piecewise harmonic-balance method, and thus retains all the peculiar advantages of this technique, including general-purposeness in the widest sense. The noise simulation capabilities include any kind of forced or autonomous nonlinear circuit operated in a time-periodic large-signal steady state, as well as microwave mixers of arbitrary topology. The limitations of the traditional frequency-conversion approach to noise analysis are overcome. The analysis takes into account the thermal noise generated in the passive subnetwork, the noise contributions of linear and nonlinear active devices, and the noise injected by sinusoidal driving sources of known statistical properties. The nonlinear noise models of two representative families of microwave devices (FET's/HEMT's and Schottky-barrier diodes) are discussed in detail, and several applications are illustrated     

Noise in RF-CMOS mixers: a simple physical model

Flicker noise in the mixer of a zero- or low-intermediate frequency (IF) wireless receiver can compromise overall receiver sensitivity. A qualitative physical model has been developed to explain the mechanisms responsible for flicker noise in mixers. The model simply explains how frequency translations take place within a mixer. Although developed to explain flicker noise, the model predicts white noise as well. Simple equations are derived to estimate the flicker and white noise at the output of a switching active mixer. Measurements and simulations validate the accuracy of the predictions, and the dependence of mixer noise on local oscillator (LO) amplitude and other circuit parameters     

Correlation between low-frequency noise and low-temperature performance of two-dimensional electron gas FET's

We report here on low-frequency (LF) noise of GaAs/ GaAlAs TEGFET's. Present investigations show that this noise is not inherently lower in TEGFET's than in MESFET's. Moreover, the bias and frequency dependence of the noise was found to indicate that traps in GaAlAs have a fundamental influence on LF noise. A close correlation is subsequently observed between the noise level at ambient temperature and the TEGFET static and dynamic performances at low temperature (130 K).     

Statistical Model for the Circuit Bandwidth Dependence of Low-Frequency Noise in Deep-Submicrometer MOSFETs

This paper covers measurement, analytical analysis, and Monte Carlo simulation of the frequency and bandwidth dependence of MOSFET low-frequency (LF) noise behavior. The model is based on microscopic device physics parameters, which cause statistical variation in the LF noise behavior of individual devices. Analytical equations for the statistical parameters are provided. The analytical model is compared to experimental data and Monte Carlo simulation results     

Robust, versatile, direct low-frequency noise characterization method for material/process quality control using cross-shaped 4-terminal devices

Low frequency (LF) noise measurement is a very sensitive tool for device quality and reliability monitoring. Despite of its potential interest, there are up to now relatively few LF noise studies combined and compared to standard reliability/quality analysis. One of the reasons is the difficulty to implement LF noise measurement on automatic wafer level testing. In this paper we promote a method using cross shaped 4 terminal devices (Hall crosses). The implementation of this method and its advantages over conventional noise measurement methods are described. This method, compatible with on-wafer probe testing, is of particular interest for material/processes quality control purposes especially for less mature material such as AlGaN/GaN Heterostructures.