10Gb/s光接收机跨阻前置放大器芯片设计研究

采用0.18 μm BiCMOS工艺设计并实现了一种高增益、低噪声、宽带宽以及大输入动态范围的光接收机跨阻前置放大器.在寄生电容为250 fF的情况下,采用全集成的四级放大电路,合理实现了上述各项参数指标间的折中.测试结果表明:放大器单端跨阻增益为73 dB,-3 dB带宽为7.6 GHz,灵敏度低至-20.44 dBm,功耗为74 mW,最大差分输出电压为200 mV,最大输入饱和光电流峰-峰值为1 mA,等效输入噪声为17.1 pA/√Hz,芯片面积为800 μ.m×950μm.     

红外傅里叶光谱仪的干涉图模型研究及应用

介绍了红外傅里叶光谱仪干涉图的获 取原理和过程。基于MATLAB软件,首次采用将数值积分技术结合 离散傅里叶变换的方法对干涉图特性进行了建模和计算,得到了不 同温度黑体辐射所对应的干涉图,并对其直流偏置、最 大值以及相对最小值等特征进行了分析。定量给出了相对最小值与直流偏 置之间的线性关系,并从试验数据上对其进行了验证。在国内首次 从干涉图特性的角度分析了大气垂直探测仪系统的背景噪 声。然后对通过在CTIA型读出电路中引入减法电路来提高动态范围的 方法进行了可行性分析。结果表明,该方法并不具有可行性。     

Throughput and energy consumption tradeoffs in path-gain-basedconstrained power control in ALOHA networks

Power control has been proposed as a tool to improve the performance of packet radio systems in terms of increased throughput and battery lifetime for mobile terminals. In this paper we study the tradeoff between transmitter dynamic range, average energy consumption and the achievable throughput for a simple path-gain based power control algorithm in a slotted ALOHA radio system. The results show that increasing the throughput significantly by means of transmitter power control requires only a very moderate increase in energy consumption and transmitter dynamic range     

A versatile high-speed bipolar charge-sensitive preamplifier forcalorimeter applications

A high-speed charge-sensitive preamplifier (CSP) to be used in silicon calorimeters has been realized. The main features of this circuit are: high slew rate (larger than 500 V/μs), low noise, large output swing (5 V), high dynamic range (of the order of 90 dB), and 50-Ω output drive capability. In addition, the CSP is designed to allow adaptation of its power-versus-noise performance to different experimental conditions. The bias current of the input device can be adjusted with an external component, in order to optimize the tradeoff between power consumption and noise. The power supply can be set in the 3.3-12-V range, optimizing the power dissipation over output swing ratio. The CSP was realized in a bipolar technology whose bipolar transistors have been previously tested before and after being subjected to irradiation. The results were taken into account in the design in order to achieve CSP radiation-hard performance     

The effects of smear on antiblooming protection and dynamic rangeof interline CCD image sensors

The effects of a smearing signal on the dynamic range and the amount of antiblooming protection of an interline CCD image sensor are presented. It is shown that there is a tradeoff between these two parameters, and that they are directly related by the amount of smear. These relationships are analyzed for both constant-integration time and constant-irradiance modes of operation. For the constant-irradiance model of operation it is shown that in order to maintain 90% of the maximum dynamic range and an antiblooming protection of 300×, the smear signal must be less than 0.037%. For the constant integration-time mode of operation, it is shown that in order to maintain 75% of a particular device's maximum dynamic range and the same amount of antiblooming protection the smear signal must be less than 0.0074%. It is also found in this mode that this relationship between antiblooming protection and the amount of linear dynamic range is exponential, and dependent on the antiblooming structure's nonideality factor and the individual photodetector's capacitance     

A cross-layer framework for optimal delay-margin,network lifetime and utility tradeoff in wireless visual sensor networks

For wireless multimedia sensor networks a distributed cross-layer framework is proposed, which not only achieves an optimal tradeoff between network lifetime and its utility but also provides end-to-end delay-margin. The delay-margin, defined as the gap between maximum end-to-end delay threshold and the actual end-to-end delay incurred by the network, is exploited by the application layer to achieve any desired level of delay quality-of-service. For optimal performance tradeoff an appropriate objective function for delay-margin is required, which is obtained by employing sensitivity analysis. Sensitivity analysis is performed by incorporating delay-margin in the end-to-end delay constraints while penalizing its price in the objective function. For distributed realization of proposed cross-layer framework, the optimal tradeoff problem is decomposed into network lifetime, utility and delay-margin subproblems coupled through dual variables. The numerical results for performance evaluation show that compromising network utility does not guarantee both lifetime and delay-margin improvement, simultaneously, for the set of operating points. Performance evaluation results also reveal that the fairness among different delay-margins, corresponding to different source–destination node pairs, can be improved by relaxing the end-to-end delay threshold.     

Efficient optimization of integrated spiral inductor with bounding of layout design parameters

In this paper we present an efficient method of determining the optimized layout of on chip spiral inductor. The method initially identifies the feasible region of optimization by developing layout design parameter bound curves for a large range of physical inductance values that satisfies the same area specification. For any desired inductance value the upper and lower bounds of the optimization variables are determined graphically. An enumeration algorithm implemented finds the global optimum layout that gives the highest quality factor in less than 1 s of CPU time with less function evaluations. The optimization method also gives the performance of all possible combinations that results the same inductance value. Subsequently important fundamental tradeoff of the design like quality factor and area, quality factor and inductance, quality factor and operating frequency, maximum quality factor and the peak frequency is explored in few seconds. The method also gives other valuable information such as sensitivity of the inductance and quality factor to the layout design parameters. The accuracy of the proposed method is verified using a 3D electromagnetic simulator.     

Full-CMOS 2-GHz WCDMA direct conversion transmitter and receiver

This paper presents a full-CMOS transmitter and receiver for 2.0-GHz wide-band code division multiple access with direct conversion mixers and a DC-offset cancellation scheme. The direct conversion scheme combined with a multiphase sampling fractional-N prescaler alleviates the problems of the direct conversion transmitter and receiver. Digital gain control is merged into the baseband filters and variable-gain amplifiers to optimize the linearity of the system, reduce the noise, and improve the sensitivity. Variable-gain amplifiers with DC-offset cancellation loop eliminate the DC-offset in each stage. The chip implemented in 0.35-/spl mu/m CMOS technology shows the experimental results of 6 dBm maximum output power with 38-dB adjacent channel power rejection ratio at 1.92 MHz, 50-dB dynamic range, and 363-mW power consumption in the transmitter. The receiver shows -115.4 dBm sensitivity, a 4.0-dB noise figure, and a dynamic range of 80-dB with 396-mW power consumption.     

Shaping multidimensional signal spaces. I. Optimum shaping, shellmapping

The structure of the regions which provide the optimum tradeoff between γ_s (shaping gain) and CER (constellation-expansion ratio) and between γ_s and PAR (peak to average power ratio) in a finite dimensional space is introduced. Analytical expressions are derived for the corresponding tradeoff curves. In general, the initial parts of the curves have a steep slope. This means that an appreciable portion of the maximum shaping gain, corresponding to a spherical region, can be achieved with a small value of CER_s, PAR. The technique of shell mapping is introduced. This is a change of variable which maps the optimum shaping region to a hypercube truncated within a simplex. This mapping is a useful tool in computing the performance, and also in facilitating the addressing of the optimum shaping region. Using the shell mapping, a practical addressing scheme is presented that achieves a point on the optimum tradeoff curves. For dimensionalities around 12, the point achieved is located near the knee of the corresponding tradeoff curve. For larger dimensionalities, a general shaping region with two degrees of freedom is used. This region provides more flexibility in selecting the tradeoff point     

高灵敏度、大动态范围光电接收电路设计与实现

无人机载的激光半主动导引头具有机动灵活、打击范围广、命中精度高等优点,在制导武器领域里占有重要的地位。为提高光电接收系统的灵敏度、动态范围和抗杂散光性能,通过对基于四象限雪崩光电二极管(QAPD)光电接收系统的分析,设计了前端信号调理电路与后端信号处理电路。试验结果表明,系统灵敏度达到了100nW,动态范围为45dB,峰值跟踪最大误差比例是1.06,在杂散光环境下可以工作正常,实现了闭环控制。研究结果对光电接收电路的设计具有一定的应用价值。     

Development and Experimental Analysis of a Soft Compliant Tactile Microsensor for Anthropomorphic Artificial Hand

This paper presents the development and preliminary experimental analysis of a soft compliant tactile microsensor (SCTM) with minimum thickness of 2 mm. A high shear sensitive triaxial force microsensor was embedded in a soft, compliant, flexible packaging. The performance of the whole system, including the SCTM, an electronic hardware and a processing algorithm, was evaluated by static calibration, maximum load tests, noise and dynamic tests, and by focusing on slippage experiments. A proper tradeoff between final robustness and sensitivity of the tactile device was identified. The experiments showed that the tactile sensor is sufficiently robust for application in artificial hands while sensitive enough for slip event detection. The sensor signals were elaborated with the cumulative summation algorithm and the results showed that the SCTM system could detect a slip event with a delay from a minimum of 24.5 ms to a maximum of 44 ms in the majority of experiments fulfilling the neurophysiological requirement.     

QoE‐ and energy‐efficient resource optimization in OFDMA networks with bidirectional relaying

Because of the surging demands of multimedia services, quality‐of‐experience (QoE) is becoming an important metric to evaluate network quality from users' perspective. In this paper, resource optimisation to achieve optimal tradeoff between QoE and energy consumption in bidirectional orthogonal frequency‐division multiple‐access relaying networks is addressed so as to provide satisfactory multimedia delivery quality and support green communications. We first formulate a QoE‐energy efficiency tradeoff optimisation where QoE requirements and relaying traffic balance are considered and prove that QoE‐energy efficiency is quasiconcave on QoE, which suggests the existence of a unique global optimal tradeoff point. We then propose an optimisation framework to achieve the optimal tradeoff efficiently. With the framework, we develop resource allocation approaches for two specific relaying strategies, that is, two‐phase decode‐and‐forward relaying with dynamic XOR network coding and compute‐and‐forward relaying with physical network coding via structured codes. Numerical results validate theoretical findings and demonstrate the effectiveness of the proposed optimisation solution for achieving the tradeoff between QoE and energy consumption. Copyright © 2015 John Wiley & Sons, Ltd.     

${K}_{a}$ –Band All-Resonant Photonic Microwave Receiver

We demonstrate a microwave photonic receiver operating at 35-GHz carrier frequency with a sensitivity exceeding ${-}$70 dBm in a 3-MHz frequency band and possessing more than 40-dB dynamic range when operated in the direct detection mode. The receiver is based on a lithium niobate optical whispering gallery mode resonator coupled to a microwave strip line resonator. We theoretically analyze the performance of the receiver and estimate its optimal achievable sensitivity and dynamic range.      

多普勒频率变化率快速最大似然估计辅助的高动态载波跟踪环路

高动态环境下接收信号含有较大的多普勒频率及其变化率,传统载波跟踪方法难以在高动态应力和跟踪精度两方面取得较好折中,针对这一问题该文提出一种多普勒频率变化率快速最大似然估计方法,并利用估计值辅助载波跟踪环路。首先指出了多普勒频率及其变化率的最大似然估计可等效采用分数阶傅里叶变换(FrFT)来实现;其次,针对频率及其变化率2维搜索运算量大的问题,提出一种瞬时自相关与分段离散傅里叶变换(DFT)求相位差相结合的频率变化率估计方法,根据粗估值可大大缩小搜索范围;最后,利用估计值辅助载波跟踪环路,降低动态应力,提高跟踪精度。理论分析与计算机仿真表明,在典型高动态参数条件下,输入信噪比为-30 dB时,搜索运算量降为原来的5.25%,输出频率的均方根误差仅为8.46 Hz/s,和传统载波跟踪方法相比,灵敏度提高3 dB以上。     

Thermal properties of power HBT's

Simulations of the thermal behavior of AlGaAs/GaAs HBT power transistors have been carried out to establish the quantitative tradeoff between power density, chip layout and junction temperatures. Numerical programs were used to model different aspects of HBT thermal behavior. These programs provide a dynamic solution for temperature distribution using a three-dimensional model which is very general in its ability to model composite chip cross sections. A model was developed to calculate threshold power densities for thermal instability. Standard and novel methods of controlling maximum temperatures in the devices are explored and evaluated. These methods include flip chip bonding and the use of partial vias. The prevention of thermal instability is described. The thermal time constants are found to have a fast component, on order of a few microseconds, and a slower component that depends on substrate thickness     

Very fast detection for rate-2 quasi-orthogonal STBCs

For an important and standard rate-two quasi-orthogonal space-time block code, we propose a very fast detection scheme which achieves a wide range of tradeoff between performance and complexity. In the proposed scheme, exploiting the special quasi-orthogonal structure of the code, we efficiently obtain multiple candidate constellation points around the maximum likelihood (ML) point. Furthermore, we develop a very fast sorting method for the multiple candidate points to further improve the detection speed. Numerical results demonstrate that the proposed scheme can perform very close to the maximum likelihood detection at an extremely low complexity.     

High-performance direct digital frequency synthesizers using piecewise-polynomial approximation

This paper presents new techniques to implement direct digital frequency synthesizers (DDFSs) with optimized piecewise-polynomial approximation. DDFS performances with piecewise-polynomial approximation are first analyzed, providing theoretical upperbounds for the spurious-free dynamic range (SFDR), the maximum absolute error, and the signal-to-noise ratio. A novel approach to evaluate, with reduced computational effort, the near optimal fixed-point coefficients which maximize the SFDR is described. Several piecewise-linear and quadratic DDFS are implemented in the paper by using novel, single-summation-tree architectures. The tradeoff between ROM and arithmetic circuits complexity is discussed, pointing out that a sensible silicon area reduction can be achieved by increasing ROM size and reducing arithmetic circuitry. The use of fixed-width arithmetic can be combined with the single-summation-tree approach to further increase performances. It is shown that piecewise-quadratic DDFSs become effective against piecewise-linear designs for an SFDR higher than 100 dBc. Third-order DDFSs are expected to give advantages for an SFDR higher than 180 dBc. The DDFS circuits proposed in this paper compare favorably with previously proposed approaches.     

Effect of nonlinearities on outage performance of fiber-fedmicrocellular networks for GMSK systems

Application of fiber for remoting the complex RF signal processing and control procedures in a microcellular system has attracted much attention. This paper investigates the effect of the laser diode nonlinearities on the outage performance of a Gaussian minimum shift keying (GMSK)-based system in a Rician channel. The analysis presented assumes that in contrast to the rapid (or short-term) fluctuations modeled by the Rician distribution, the slow (or long-term) fluctuations due to shadowing or near-far effects are compensated (in an exact sense) by power control schemes. The nonlinearity of the laser diode is shown to create a tradeoff between the outage and system parameters such as radio capacity and threshold bit-error rate (BER). The optical noises, such as shot noise, thermal noise, and relative intensity noise, are shown to degrade the outage of the system. Also, in addition to the usual improvement of outage with a strong specular component, it is observed that the specularity of the channel in a small measure mitigates the effective nonlinearity of the system and thus increases the dynamic range of the system. Design equations are provided for optimal performance     

A design for the additional members of the transitional Mucromaf-Mucroer filters

The design technique for transitional Mucromaf-Mucroer filters is extended to cover the complete set of transitional members. It provides a designer with an extensive, tradeoff between the sensitivity performance and the selectivity characteristics for active filters.     

On the diversity gain region of the dynamic decode-and-forward relay-assisted Z-channel

In an interference-limited system, the interference forwarding by a relay enhances the interference level and thereby enables the cancellation of the interference. In this work, interference forwarding by a half-duplex dynamic decode-and-forward (HD DDF) relay in a two-user Z-channel is considered. In the two-user Z-channel, one user is interference-limited while the other user is interference-free. The diversity gain region (DGR), which characterizes the tradeoff between the achievable diversity orders between the two users, is an appropriate performance metric for the Z-channel. Closed-form expression for the achievable DGR with the interference forwarding by the HD DDF relay is presented. The multiplexing gain regions (MGRs) where the HD DDF protocol achieves better DGR over the direct transmission scheme, full-duplex decode-and-forward (FD DF) and FD partial DF relay assisted Z- channel are identified. The HD DDF protocol is shown to achieve better DGR than the FD DF and FD PDF relay for a large range of MGR. The achievable DGRs for the HD DDF, FD DF, and FD PDF relay-assisted Z-channel and direct transmission scheme are presented for various interference levels and multiplexing gain pairs.