Simulation of a Monolithic Integrated CMOS Preamplifier for Neural Recordings

提出一种用于提取神经电信号的新型单片集成CMOS前置放大器.在放大器输入端引入的交流耦合电容可以消除存在于电极-电解液之间的电极极化电压,栅源电压为负值的二极管连接的nMOS晶体管能够作为大电阻,并且占用很小芯片面积,可以通过此大电阻为前置放大器提供直流偏置,同时不影响输入阻抗值.通过对输入级进行理论噪声分析,确定了放大器中的各个器件参数.仿真结果表明,由于采用电容负反馈结构,此放大器的交流增益为38.8dB,无直流增益,在0.1Hz～1kHz频率范围内,总输入等效噪声为277nVrms.     

提取神经电信号的单片集成CMOS前置放大器的仿真研究

提出一种用于提取神经电信号的新型单片集成CMOS前置放大器.在放大器输入端引入的交流耦合电容可以消除存在于电极-电解液之间的电极极化电压,栅源电压为负值的二极管连接的nMOS晶体管能够作为大电阻,并且占用很小芯片面积,可以通过此大电阻为前置放大器提供直流偏置,同时不影响输入阻抗值.通过对输入级进行理论噪声分析,确定了放大器中的各个器件参数.仿真结果表明,由于采用电容负反馈结构,此放大器的交流增益为38.8dB,无直流增益,在0.1Hz～1kHz频率范围内,总输入等效噪声为277nVrms.     

Two-section reversed /spl Delta//spl beta/ switch with uniform electrodes and domain reversal

The performance of the reversed-/spl Delta//spl beta/ LiNbO/sub 3/ optical directional coupler (DC) switch with electrodes of opposite polarity is known to be more tolerant to variations in coupling length than that of the single-section DC. However, sectioned electrodes are incompatible to a single microwave source and, therefore, preclude the use of the device in high-speed applications. In this letter, we discuss the operation and results of a modified DC that uses a domain reversal and uniform electrodes that can be readily matched to a microwave source. A crosstalk of -34 dB was measured in an experimental device, fabricated in Z-cut LiNbO/sub 3/. Factors which improve device performance are also discussed.     

交直流仪表现场标准源设计

文章给出了交直流仪表现场标准源的主要特点和技术指标,并详细介绍了交直流仪表现场标准源的工作原理。     

基于高阶循环累积量的SQAM信号调制识别算法

该文利用通信信号的循环平稳特性,在循环累积量域内构造信号分类特征,提出了一种基于高阶循环累积量的调制识别算法,实现对SQAM信号分类。算法对载波频率偏差、时延和相位旋转具有稳健性,并可在多信号环境且存在载波频偏的情况下实现对感兴趣信号的识别。理论分析和仿真结果均证明了算法的正确性和有效性。     

Study of the impact of hot carrier injection to immunity of MOSFET to electromagnetic interferences

This paper presents an original study about the effect of hot carrier injection stress on the DC offsets induced by electromagnetic interferences (EMI) on a nanometric NMOS transistor, which is one of the major sources of failures in analog circuits. Measurements and simulations based on a simple model (Sakurai–Newton model) of fresh and stressed transistors are presented and show significant variations of EMI-induced DC shifts of drain current.     

Thermoelectric Energy Harvesting from Transient Ambient Temperature Gradients

We examine a thermoelectric harvester that converts electrical energy from the naturally occurring temperature difference between ambient air and large thermal storage capacitors such as building walls or the soil. For maximum power output, the harvester design is implemented in two steps: source matching of the thermal and electrical interfaces to the energy source (system level) followed by load matching of the generator to these interfaces (subsystem level). Therefore, we measure thermal source properties such as the temperature difference, the air velocity, and the cutoff frequency in two application scenarios (road tunnel and office building). We extend a stationary model of the harvester into the time domain to account for transient behavior of the source. Based on the model and the source measurements, we perform the source and load matching. The resulting harvester consists of a pin fin heat sink with a thermal resistance of 6.2?K/W and a cutoff frequency 2.5?times greater than that of the source, a thermoelectric generator, and a DC/DC step-up converter starting at a total temperature difference of only ??T?=?1.2?K. In a final road tunnel field test, this optimized harvester converts 70?mJ of electrical energy per day without any direct solar irradiation. The energy provided by the harvester enables 415?data transmissions from a wireless sensor node per day.     

Precision current and charge amplifiers for driving highly capacitive piezoelectric loads

Piezoelectric transducers are known to be highly capacitive loads that exhibit less hysteresis when driven with current or charge rather than voltage. Compliance feedback current and charge amplifiers are introduced. A secondary output voltage feedback loop is employed to prevent DC charging of capacitive loads and to compensate for any voltage or current offsets in the driver circuit. Low frequency bandwidths in the milliHertz range can be achieved.     

Chopper stabilised ΠΔΣ analogue to digitalconversion

A chopper stabilised ΠΔΣ ADC architecture is proposed. A chopper stabilised version of ΠΔΣ ADC, which has identical performances to the regular ΠΔΣ ADC but is immune to low frequency noises such as DC offsets, can be obtained without adding hardware complexities     

内应力对玻璃包覆钴基非晶丝巨磁阻抗的影响

通过测量玻璃包覆钴基非晶丝、去除玻璃包覆层非晶丝和经直流焦耳热退火后玻璃包覆非晶丝的磁阻抗值,研究了玻璃包覆层和直流退火对玻璃包覆钴基非晶丝内应力及巨磁阻抗效应的影响。结果表明:通过处理,玻璃包覆非晶丝的GMI最大值更容易在弱磁场出现;随着淬火残余内应力的改变,导致样品壳内畴的体积增加,引起应力感生横向各向异性,从而增强GMI效应;其中经90mA直流退火的样品GMI峰值最大可达144%。     

基于可变激光源和啁啾M-Z调制器的双调谐光电振荡器

设计了一种利用微波光子滤波器(MPF)实现频率可调谐的光电振荡器(OEO)。该模型通过双驱动Mach-Zehnder调制器(DD-MZM)和啁啾光栅形成高Q值的MPF,得出OEO的振荡频率是关于光源波长和DD-MZM直流偏置电压的函数,通过对光源波长或DD-MZM偏置电压的调整,可实现振荡频率调谐功能。同时,在电域上,利用RF耦合器和RF延时线形成两路具有延时差的反馈信号,通过合并后反馈至DD-MZM,从而有效地抑制边模。理论和仿真实验表明,针对不同的调谐范围可实现粗调和微调的功能。     

Torque and velocity ripple elimination of AC permanent magnet motor control systems using the internal model principle

This paper addresses the problem of torque and velocity ripple elimination in AC permanent magnet (PM) motor control systems. The torque ripples caused by DC offsets that are present in the current sensors of the motor driver and the digital-to-analog converters of the motion controller are studied and formulated mathematically. These torque ripples eventually generate velocity ripples at the speed output and degrade the system performance. In this paper the torque ripples are modeled as a sinusoidal function with a frequency depending on the motor speed. The internal model principle (IMP) is then used to design a controller to eliminate the torque and velocity ripples without estimating the amplitude and the phase values of the sinusoidal disturbance. A gain scheduled (GS) robust two degree of freedom (2DOF) speed regulator based on the IMP and the pole-zero placement is developed to eliminate the torque and velocity ripples and achieve a desirable tracking response. Simulation and experimental results reveal that the proposed GS robust 2DOF speed regulator can effectively eliminate the torque ripples generated by DC current offsets, and produce a velocity ripple-free output response.     

分布式MIMO系统多分量调制信号频率估计

针对分布式多输入多输出系统中的多频偏估计问题进行了研究,提出一种多分量调制信号的高分辨率频率盲估计方法。该方法避免了直接对多分量调制信号进行稀疏表示,无需导频等先验信息,避免传统频率估计方法中的内插、去相位混叠等处理,可一次性精确估计出所有信号频率。通过正定盲源分离方法从接收信号中分离出多个源信号,经过盲去调制处理,将其转换成多单频信号,根据多单频信号的稀疏表示,利用一个随机的压缩矩阵对信号进行压缩,再在压缩域中通过 模优化重构该稀疏信号,获得频率估计。仿真结果表明,与现有算法相比,所提方法可在少数据量、低信噪比下获得高精度估计性能,可在5dB时达到1e-6的平均均方误差。      

二维直接DCIM计算分层介质空域格林函数

二维离散复镜像法(discrete complex image method,DCIM)可以有效计算分层介质中场源点位于不同介质层时的空域格林函数,但在场源点距离大于波长时的计算结果不准确。本文采用二维DCIM结合直接DCIM二级路径的方法,研究了多层微带结构中场源点位于不同介质层时空域格林函数的计算问题;通过单层和两层微带结构空域格林函数的计算实例,分析了积分路径对格林函数计算精度的影响。结果表明:采用直接DCIM二级路径的二维DCIM方法可以准确计算分层介质中场源点距离大于10倍波长时的空域格林函数。     

Magnetic bubble memory linear interface circuits

Two bipolar integrated circuits are described which provide the write and sense functions required by magnetic bubble memory systems, both organized in four-channel format to minimize board area occupied. The write driver circuit has a 300 mA drive capability and includes on-chip circuitry which prevents fusing of the delicate bubble `hairpin' structure under fault conditions. The sense amplifier has programmable sensitivity in the range of 1 mV to 10 mV and allows the bubble device to be directly coupled to the differential input while tolerating DC offsets of up to /spl plusmn/150 mV without significantly modifying sensitivity.     

Power electronics in German railway propulsion

The state of the art of power electronics is reviewed. Because of the different requirements, such as suburban or long distance traffic and DC or AC supply, various systems are in use and some peculiar configurations, as resistor braking, have become important. With AC supply special line-commutated rectifiers causing low displacement factor and small harmonic content are used for DC motor propulsion. With DC supply choppers allow nondissipative motor control, often combined with special circuits for field weakening and for change of driving/breaking. Particularly important is three-phase propulsion with robust squirrel-cage motors, made possible by the development of suitable variable-frequency inverters. Both current source and voltage source inverters are used in suburban cars as well as for locomotive drives. The most universal but also most complicated system served by the voltage source inverter is described in more detail     

Analysis of quantized feedback low-frequency restoration in digitalregenerators

Quantized feedback, a DC restoration technique utilizing decision feedback equalization, can be used to compensate for unavoidable low-frequency cutoff in digital regenerators. An analysis is provided of the error probability and sensitivity to timing offsets of quantized feedback for a single-pole high-pass filter regenerator characteristic. Error probability is expressed in terms of the moments of the intersymbol interference (ISI), and these moments are calculated using the Markov chain properties of the ISI. To keep degradations small, the low-frequency cutoff should be no greater than 15% of the bit rate     

非理想载波同步物理层网络编码误比特性能分析

采用相干检测的物理层网络编码系统的误比特性能与载波同步精度密切相关,收发双方的载波同步误差将引起系统性能恶化。本文研究了残余载波同步误差对采用相同星座和正交星座BPSK信号的两种物理层网络编码双向中继系统误比特性能的影响。首先基于最大似然准则推导了存在残余载波同步误差时中继节点及源节点处接收信号的判决区域,然后运用Craig极坐标法分析了系统多址接入、广播阶段及总的端到端误比特性能,得出了精确的误比特率表达式,文中的分析方法可推广到采用其他调制方式的物理层网络编码系统。计算机仿真表明:文中的理论分析与仿真结果完全吻合,所推导的理论公式可以效地评估BPSK调制物理层网络编码系统的误比特性能;正交星座系统对载波同步误差更为敏感,相同的同步误差对正交星座系统的性能恶化更为严重。      

Robustness to laser frequency offset in direct-detection DPSK and DQPSK systems

We assess, both by measurement and simulation, the receiver performance degradation caused by frequency offsets between the optical source and the delay interferometer for nonreturn-to-zero (NRZ) and return-to-zero (RZ) differential-phase-shift-keying (DPSK) and differential-quadrature-phase-shift-keying (DQPSK) systems. We find that NRZ- and RZ-DQPSK systems are about six times more sensitive to frequency offsets than NRZ- and RZ-DPSK systems operating at the same bit rate. We explain the reason for this behavior by means of eye aperture considerations.     

基于DVB-T的OFDM频偏估计算法及DSP实现

由于OFDM调制是基于载波间正交的调制方式,频偏存在会使载波间正交性破坏,进而影响解调和性能。基于DVB-T提出了一种基于时域和频域相结合的频偏估计算法并对性能进行了仿真分析,并结合项目实际给出了DSP实现方法,最后对DSP实现后的数据进行了星座图验证和项目最后ARM接收端接收数据的验证。结果表明此算法对解决DVB-T物理层的频偏非常有效。