共查询到19条相似文献，搜索用时 421 毫秒
1.
小波函数和小波变换网络的瞬时缩展技术综合是电网络综合的新理论、新方法．本文利用对数域电路实现连续小波变换，提出的模拟CMOS高频连续小波变换电路能实现高频输入信号的时频分解，电路中的振荡器电路采用的是完全的电流模式对数域电路．并由此对数域振荡器设计和实现电流模式锁相环，从而提出了模拟连续小波变换的电路设计和实现、结果显示电路能在低电压低功率时得到宽动态范围的运用、 相似文献
2.
该无线音频传输系统以功率型白光LED作为传输媒介,主要由音频信号调制电路、LED驱动电路、锁相环译码还原电路、音频功放电路组成。该系统利用多谐振荡器电路产生的载波对输入音频信号进行模拟调制后送LED驱动电路进行发射传输。LED发射的光信号被硅光电池接收,经过锁相环电路解调并滤除高频载波得到原有的输入音频信号。实验测试结果表明,该系统在2 m范围内能较好实现输入频率为200 Hz~2 k Hz的音频信号传输,对室内可见光通信应用具有一定的参考价值。 相似文献
3.
利用负电阻提高LC振荡电路性能 总被引：3，自引：0，他引：3
目的对LC振荡电路频率稳定度进行了分析，指出了LC回路等效损耗内阻是影响其主要原因．方法采用在电路中加入同LC回路等效损耗内阻相同大小的负电阻，以减小内阻对LC振荡器的影响．结果加入负电阻后，电路的频率稳定度明显提高，同时也极大的提高了电路的品质因数，使电路的选择性更好．结论加入负电阻的振荡器，理论上性能接近理想振荡器． 相似文献
4.
讨论了集成单稳态触发器74121触发输入端和引脚11的输入特性,深入分析了影响74121单稳态电路暂稳时间的因素。提出了4种用单片74121构成的自激多谐振荡器电路,分别讨论了它们的工作原理,研究了振荡频率的计算公式,并用实际测试的结果进行了对比分析。理论分析和实验结果证明,74121构成单稳态电路时,定时元件的取值范围可以适当增大,单片74121振荡器电路方案可行。 相似文献
5.
介绍一种在８０９８单片机控制下的远距离多路数据采集系统电路，该电路可实现２５６路的信号采集，并对不同幅度信号自动增益控制，使信号采集的精度处于最佳状态。该电路具有一定的应用价值。 相似文献
6.
无线电振幅调制电路设计 总被引：1，自引：0，他引：1
基带信号直接通过天线传送出去的不合理性,决定了用待传输的基带信号去控制高频载波参数电路的必要性。推导分析普通调幅、抑制载波的双边带调幅、单边带调幅的调幅表达式、调制波形、频谱分布。采用多频基带信号作为输入,设计无线电发射机的振幅调制电路。利用示波器观察实验结果,验证调幅电路的可行性。 相似文献
7.
提出了一种新的采用ΣΔ调制和无损离散积分振荡器来产生片内模拟信号的方法.研究了电路的实现原理和噪声传递函数零点优化设计方法,运用无乘法器的梯型滤波器结构和ΣΔ调制技术避免了多位高精度乘法运算和多位D/A数模转换器硬件成本高的缺点.除一个比较器外,整个电路全部由标准CMOS工艺来实现集成,硬件成本非常低,非常适用基于可测性混合集成电路的设计.通过一个6阶实例和仿真的结果表示:6阶的信号发生器具有120 dB衰减的动态带宽. 相似文献
8.
王国玲 《厦门水产学院学报》2011,(6):471-475
研究了单相数控Boost型有源功率因数校正系统,采用平均电流型控制策略,分析了功率电路、信号调理电路、驱动电路的实现方案.采用DSP实现系统的数字控制,深入探讨了3个模拟采样信号和乘法器增益的确定方法,以及PI控制与PWM占空比算法,并对系统软启动、A/D转换、输入电压前馈和PWM信号产生4个程序模块进行了分析,仿真结果表明了系统设计的正确性. 相似文献
9.
为满足振荡器高频低噪声的要求,设计了一种100 MHz低噪声恒温石英晶体振荡器.该振荡器选用AT切型高Q值无谐波石英谐振器;主振电路采用并联型电路结构;主振管采用Rbb′小,fT高和NF小的低噪声管以达到降噪目的;主振级与输出级之间加入T型匹配网络以增大主振级输出功率;输出级采用并联谐振电路以提高频谱纯度.样品通过测试,其相位噪声为-165 dB/Hz@10 kHz. 相似文献
10.
利用车辆绕环岛交织行驶在“空间”上解决了道路相交车辆的冲突问题,但其占地大、增加车辆绕行、主次道路相交时,主干道车辆不能优先通行.为改善环形交叉口的交通状况,采取环岛加信号控制的方法,在时间和空间上充分利用环形交叉口的资源,提高了其通行能力.在本论文中对环形交叉口的环岛半径、交织段长度、环道宽度、出口半径及外缘的平面线... 相似文献
11.
Chen Z Appenzeller J Lin YM Sippel-Oakley J Rinzler AG Tang J Wind SJ Solomon PM Avouris P 《Science (New York, N.Y.)》2006,311(5768):1735
Single-walled carbon nanotubes (SWCNTs) have been shown to exhibit excellent electrical properties, such as ballistic transport over several hundred nanometers at room temperature. Field-effect transistors (FETs) made from individual tubes show dc performance specifications rivaling those of state-of-the-art silicon devices. An important next step is the fabrication of integrated circuits on SWCNTs to study the high-frequency ac capabilities of SWCNTs. We built a five-stage ring oscillator that comprises, in total, 12 FETs side by side along the length of an individual carbon nanotube. A complementary metal-oxide semiconductor-type architecture was achieved by adjusting the gate work functions of the individual p-type and n-type FETs used. 相似文献
12.
哺乳动物昼夜节律生物钟是以24 h为周期的自主维持的振荡器。在分子水平上,生物钟的振荡由自身调控反馈环路的转录和翻译组成,并接受外界环境因素的影响,通过下丘脑视叉上核(Supra Ch iasm atic N u-cleus,SCN)中枢震荡器的同步整和而产生作用。文章对生物钟上下游的分布、反馈环路的转录、翻译后事件、视觉通路、钟的整和等方面进行了综述,并对其今后的研究方向作了展望。 相似文献
13.
We demonstrate logic circuits with field-effect transistors based on single carbon nanotubes. Our device layout features local gates that provide excellent capacitive coupling between the gate and nanotube, enabling strong electrostatic doping of the nanotube from p-doping to n-doping and the study of the nonconventional long-range screening of charge along the one-dimensional nanotubes. The transistors show favorable device characteristics such as high gain (>10), a large on-off ratio (>10(5)), and room-temperature operation. Importantly, the local-gate layout allows for integration of multiple devices on a single chip. Indeed, we demonstrate one-, two-, and three-transistor circuits that exhibit a range of digital logic operations, such as an inverter, a logic NOR, a static random-access memory cell, and an ac ring oscillator. 相似文献
14.
We demonstrate universal computation in an all-fluidic two-phase microfluidic system. Nonlinearity is introduced into an otherwise linear, reversible, low-Reynolds number flow via bubble-to-bubble hydrodynamic interactions. A bubble traveling in a channel represents a bit, providing us with the capability to simultaneously transport materials and perform logical control operations. We demonstrate bubble logic AND/OR/NOT gates, a toggle flip-flop, a ripple counter, timing restoration, a ring oscillator, and an electro-bubble modulator. These show the nonlinearity, gain, bistability, synchronization, cascadability, feedback, and programmability required for scalable universal computation. With increasing complexity in large-scale microfluidic processors, bubble logic provides an on-chip process control mechanism integrating chemistry and computation. 相似文献
15.
甘治国 《上海交通大学学报(农业科学版)》1988,(3)
本文提供了一个应用SHARP PC-1500微机进行定时自动控制的方案。应用该方案构成的两通道定时控制系统,具有良好的性能指标,可对工农业生产过程和科学实验过程进行定时自动控制。文中阐述了该方案的基本原理;提供了全部程序,并对程序进行了解说;介绍了接口电路;阐述了实施该方案的技术措施。 相似文献
16.
Minlebaev M Colonnese M Tsintsadze T Sirota A Khazipov R 《Science (New York, N.Y.)》2011,334(6053):226-229
During development, formation of topographic maps in sensory cortex requires precise temporal binding in thalamocortical networks. However, the physiological substrate for such synchronization is unknown. We report that early gamma oscillations (EGOs) enable precise spatiotemporal thalamocortical synchronization in the neonatal rat whisker sensory system. Driven by a thalamic gamma oscillator and initially independent of cortical inhibition, EGOs synchronize neurons in a single thalamic barreloid and corresponding cortical barrel and support plasticity at developing thalamocortical synapses. We propose that the multiple replay of sensory input in thalamocortical circuits during EGOs allows thalamic and cortical neurons to be organized into vertical topographic functional units before the development of horizontal binding in adult brain. 相似文献
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Kim DH Ahn JH Choi WM Kim HS Kim TH Song J Huang YY Liu Z Lu C Rogers JA 《Science (New York, N.Y.)》2008,320(5875):507-511
We have developed a simple approach to high-performance, stretchable, and foldable integrated circuits. The systems integrate inorganic electronic materials, including aligned arrays of nanoribbons of single crystalline silicon, with ultrathin plastic and elastomeric substrates. The designs combine multilayer neutral mechanical plane layouts and "wavy" structural configurations in silicon complementary logic gates, ring oscillators, and differential amplifiers. We performed three-dimensional analytical and computational modeling of the mechanics and the electronic behaviors of these integrated circuits. Collectively, the results represent routes to devices, such as personal health monitors and other biomedical devices, that require extreme mechanical deformations during installation/use and electronic properties approaching those of conventional systems built on brittle semiconductor wafers. 相似文献
19.
GABA (gamma-aminobutyric acid), the major inhibitory transmitter in the brain, goes through a transitory phase of excitation during development. The excitatory phase promotes neuronal growth and integration into circuits. We show here that spontaneous nicotinic cholinergic activity is responsible for terminating GABAergic excitation and initiating inhibition. It does so by changing chloride transporter levels, shifting the driving force on GABA-induced currents. The timing of the transition is critical, because the two phases of GABAergic signaling provide contrasting developmental instructions. Synergistic with nicotinic excitation, GABAergic inhibition constrains neuronal morphology and innervation. The results reveal a multitiered activity-dependent strategy controlling neuronal development. 相似文献