Many CAD users dismiss schematic capture as a necessary evil in the process of creating\r\nPCB layout but we have always disputed this point of view. With PCB layout now offering\r\nautomation of both component placement and track routing, getting the des
标签： schematic necessary creating dismiss
上传时间： 2013-09-25
上传用户：baiom
微弱信号检测装置 四川理工学院 刘鹏飞、梁天德、曾学明 摘要： 本设计以TI的Launch Pad为核心板，采用锁相放大技术设计并制作了一套微弱信号检测装置，用以检测在强噪声背景下已知频率微弱正弦波信号的幅度值，并在液晶屏上数字显示出所测信号相应的幅度值。实验结果显示其抗干扰能力强，测量精度高。 关键词：强噪声；微弱信号；锁相放大；Launch Pad Abstract: This design is based on the Launch Pad of TI core board, using a lock-in amplifier technique designed and produced a weak signal detection device, to measure the known frequency sine wave signal amplitude values of the weak in the high noise background, and shows the measured signal amplitude of the corresponding value in the liquid crystal screen. Test results showed that it has high accuracy and strong anti-jamming capability. Keywords: weak signal detection; lock-in-amplifier; Launch Pad 1、引言 随着现代科学技术的发展，在科研与生产过程中人们越来越需要从复杂高强度的噪声中检测出有用的微弱信号，因此对微弱信号的检测成为当前科研的热点。微弱信号并不意味着信号幅度小，而是指被噪声淹没的信号，“微弱”也仅是相对于噪声而言的。只有在有效抑制噪声的条件下有选择的放大微弱信号的幅度，才能提取出有用信号。微弱信号检测技术的应用相当广泛，在生物医学、光学、电学、材料科学等相关领域显得愈发重要。 2、方案论证 针对微弱信号的检测的方法有很多，比如滤波法、取样积分器、锁相放大器等。下面就针对这几种方法做一简要说明。 方案一：滤波法。 在大部分的检测仪器中都要用到滤波方法对模拟信号进行一定的处理，例如隔离直流分量，改善信号波形，防止离散化时的波形混叠，克服噪声的不利影响，提高信噪比等。常用的噪声滤波器有：带通、带阻、高通、低通等。但是滤波方法检测信号不能用于信号频谱与噪声频谱重叠的情况，有其局限性。虽然可以对滤波器的通频带进行调节，但其噪声抑制能力有限，同时其准确性与稳定性将大打折扣。
上传时间： 2013-11-04
上传用户：lty6899826
Abstract: Many digital devices incorporate analog circuits. For instance, microprocessors, applicationspecificintegrated circuits (ASICs), and field-programmable gate arrays (FPGAs) may have internalvoltage references, analog-to-digital converters (ADCs) or digital-to-analog converters (DACs). However,there are challenges when you integrate more analog onto a digital design. As with all things in life, inelectronics we must always trade one parameter for another, with the application dictating the propertrade-off of analog function. In this application note, we examine how the demand for economy of spaceand cost pushes analog circuits onto digital substrates, and what design challenges emerge.
上传时间： 2013-11-16
上传用户：菁菁聆听
Abstract: This tutorial discusses proper printed-circuit board (PCB) grounding for mixed-signal designs. Formost applications a simple method without cuts in the ground plane allows for successful PCB layouts withthis kind of IC. We begin this document with the basics: where the current flows. Later, we describe how toplace components and route signal traces to minimize problems with crosstalk. Finally, we move on toconsider power supply-currents and end by discussing how to extend what we have learned to circuits withmultiple mixed-signal ICs.
上传时间： 2013-11-04
上传用户：pol123
Abstract: This application note describes how to design boost converters using the MAX17597 peakcurrent-mode controller. Boost converters can be operated in discontinuous conduction mode (DCM) orcontinuous conduction mode (CCM). This operating mode can affect the component choices, stress levelin power devices, and controller design. Formulas for calculating component values and ratingsare alsopresented.
上传时间： 2013-11-15
上传用户：zcs023047
Abstract: This application note describes how sampling clock jitter (time interval error or "TIE jitter") affectsthe performance of delta-sigma digital-to-analog converters (DACs). New insights explain the importanceof separately specifying low-frequency (< 2x passband frequency) and high-frequency or wideband (> 2xpassband frequency) jitter tolerance in these devices. The article also provides an application example ofa simple highly jittered cycle-skipped sampling clock and describes a method for generating a properbroadband jittered clock. The document then goes on to compare Maxim's audio DAC jitter tolerance tocompetitor audio DACs. Maxim's exceptionally high jitter tolerance allows very simple and low-cost sampleclock implementations.
上传时间： 2013-10-25
上传用户：banyou
Abstract: Most magnetic read head data sheets do not fully specify the frequency-dependent components andare often vague when specifying other key parameters. In some cases, the specifications of two very similarheads from two different manufacturers might be quite different in terms of parameters specified and omitted.The limitations in the data sheets make designing an optimum card reading system unnecessarily difficult andtime consuming. This document outlines a strategy to overcome the above shortcomings and offers guidelinesto overcome the noise issues.
上传时间： 2013-11-12
上传用户：dysyase
Abstract: Perfection is relative and application specific. The perfect race car is not the car we use to commute to work. We need products for everyday use that are high quality, affordable, and solidly reliable. There will be times when we must use components that are not perfect, and this is when calibration becomes important. Calibration techniques reduce tolerances in imperfect manufacturing equipment while maintaining affordability.
标签： 校准
上传时间： 2013-10-09
上传用户：哈哈hah
Abstract: Alexander Graham Bell patented twisted pair wires in 1881. We still use them today because they work so well. In addition we have the advantage ofincredible computer power within our world. Circuit simulators and filter design programs are available for little or no cost. We combine the twisted pair and lowpassfilters to produce spectacular rejection of radio frequency interference (RFI) and electromagnetic interference (EMI). We also illustrate use of a precision resistorarray to produce a customizable differential amplifier. The precision resistors set the gain and common mode rejection ratios, while we choose the frequencyresponse.
上传时间： 2014-11-26
上传用户：Vici
Abstract: For many first-time users, finding the right logger that meets their needs can be a challenging task. In simple
上传时间： 2014-01-18
上传用户：缥缈
