本文将接续介绍电源与功率电路基板，以及数字电路基板导线设计。宽带与高频电路基板导线设计a.输入阻抗1MHz，平滑性(flatness)50MHz 的OP增幅器电路基板图26 是由FET 输入的高速OP 增幅器OPA656 构成的高输入阻抗OP 增幅电路，它的gain取决于R1、R2，本电路图的电路定数为2 倍。此外为改善平滑性特别追加设置可以加大噪讯gain，抑制gain-频率特性高频领域时峰值的R3。图26 高输入阻抗的宽带OP增幅电路图27 是高输入阻抗OP 增幅器的电路基板图案。降低高速OP 增幅器反相输入端子与接地之间的浮游容量非常重要，所以本电路的浮游容量设计目标低于0.5pF。如果上述部位附着大浮游容量的话，会成为高频领域的频率特性产生峰值的原因，严重时频率甚至会因为feedback 阻抗与浮游容量，造成feedback 信号的位相延迟，最后导致频率特性产生波动现象。此外高输入阻抗OP 增幅器输入部位的浮游容量也逐渐成为问题，图27 的电路基板图案的非反相输入端子部位无full ground设计，如果有外部噪讯干扰之虞时，接地可设计成网格状(mesh)。图28 是根据图26 制成的OP 增幅器Gain－频率特性测试结果，由图可知即使接近50MHz频率特性非常平滑，-3dB cutoff频率大约是133MHz。
标签： PCB
上传时间： 2013-11-13
上传用户：hebanlian
Abstract: Rail splitting is creating an artificial virtual ground as a reference voltage. It is used to set the signalto match the op amp's "sweet spot." An op amp has the most linear- and distortion-free qualities at that sweetspot. Typically, the sweet spot occurs near the center between the single power rail and ground. In the case ofa number of signals, the virtual ground can control channel DC errors when multiplexing or switching thesignals.
上传时间： 2013-10-23
上传用户：wushengwu
What would happen if someone connected 24V to your12V circuits? If the power and ground lines were inadvertentlyreversed, would the circuits survive? Does yourapplication reside in a harsh environment, where the inputsupply can ring very high or even below ground? Evenif these events are unlikely, it only takes one to destroya circuit board.
上传时间： 2013-10-26
上传用户：jackandlee
The above title is not happenstance and was arrived at afterconsiderable deliberation. As a linear IC manufacturer, it isour goal to encourage users to design and build switchingregulators. A problem is that while everyone agrees thatworking switching regulators are a good thing, everyonealso agrees that they are difficult to get working. Switchingregulators, with their high efficiency and small size, areincreasingly desirable as overall package sizes shrink.Unfortunately, switching regulators are also one of themost difficult linear circuits to design. Mysterious modes,sudden, seemingly inexplicable failures, peculiar regulationcharacteristics and just plain explosions are commonoccurrences. Diodes conduct the wrong way. Things gethot that shouldn’t. Capacitors act like resistors, fusesdon’t blow and transistors do. The output is at ground, andthe ground terminal shows volts of noise.
标签： Regulators Switching Poets for
上传时间： 2013-12-19
上传用户：奇奇奔奔
Demonstration circuit 1562A is an engineering toolto design and evaluate the LTC699X-X family ofTimerBlox circuits. The center section of the boardcontains a pre-configured TimerBlox function.DC1562A comes in twelve timing function variationsas outlined in Table 1.Surrounding the center board is a ”playground”prototyping area. The prototyping area has padsfor Dip-8, S8, MS8, or S6 packages with breadboarding connections to each pin and two convenientpower buses and ground bus surrounding theentire area. This area is for conditioning signals tocontrol the timer function and for adding loads controlled in time.
上传时间： 2013-10-18
上传用户：如果你也听说
The ISO7220 and ISO7221 are dual-channel digital isolators. To facilitate PCB layout, the channels are orientedin the same direction in the ISO7220 and in opposite directions in the ISO7221. These devices have a logic inputand output buffer separated by TI’s silicon-dioxide (SiO2) isolation barrier, providing galvanic isolation of up to4000 V. Used in conjunction with isolated power supplies, these devices block high voltage, isolate grounds, andprevent noise currents on a data bus or other circuits from entering the local ground and interfering with ordamaging sensitive circuitry.
上传时间： 2013-10-24
上传用户：hbsunhui
SM-IIC/2051 模块用户说明简介：SM-IIC/2051 是一个基于2051 单片机的I2C 总线控制模块。上位机接口可直接与PC的RS232 连接，下位机可实现对应用电路中I2C 控制总线的连接，块内设置2K 的FLASH 存储器，可存储用户I2C 初始化数据。模块采用2051 单片机，使电路简单可靠。型号：SM-IIC/2051名称：I2C 数据控制模块功能：RS232 串行信号与I2C 数据转换 接口说明：编号信号标志信号名称规格备注CK1-1 VCC 供电+5VCK1-2 VCC 供电+5VCK1-3 GND 地groundCK1-4 GND 地groundCK2-1 TOUT 串口输出RS232CK2-2 RIN 串口输入RS232CK2-3 GND 地groundCK2-4 GND 地ground编号信号标志信号名称规格备注CK3-1 GND 地groundCK3-2 SCL I2C 时钟TTLCK3-3 SDA I2C 数据TTLCK3-4 GND 地groundCK3-5 P1.2 PI/O 端口TTLCK3-6 P1.3 PI/O 端口TTLCK3-7 P1.4 PI/O 端口TTLCK3-8 P1.5 PI/O 端口TTLCK3-9 P1.6 PI/O 端口TTLCK3-10 P1.7 PI/O 端口TTLCK3-11 P3.7 PI/O 端口TTLCK3-12 T1 定时端口TTLCK3-13 T0 定时端口TTLCK3-14 INT1 中断端口TTLCK3-15 INT0 中断端口TTLCK3-16 GND 地ground
上传时间： 2013-11-18
上传用户：爺的气质
Prakash Rashinkar has over 15 years experience in system design and verificationof embedded systems for communication satellites, launch vehicles and spacecraftground systems, high-performance computing, switching, multimedia, and wirelessapplications. Prakash graduated with an MSEE from Regional Engineering College,Warangal, in India. He lead the team that was responsible for delivering themethodologies for SOC verification at Cadence Design Systems. Prakash is anactive member of the VSIA Functional Verification DWG. He is currently Architectin the Vertical Markets and Design Environments Group at Cadence.
上传时间： 2014-01-24
上传用户：xinhaoshan2016
Prakash Rashinkar has over 15 years experience in system design and verificationof embedded systems for communication satellites, launch vehicles and spacecraftground systems, high-performance computing, switching, multimedia, and wirelessapplications. Prakash graduated with an MSEE from Regional Engineering College,Warangal, in India. He lead the team that was responsible for delivering themethodologies for SOC verification at Cadence Design Systems. Prakash is anactive member of the VSIA Functional Verification DWG. He is currently Architectin the Vertical Markets and Design Environments Group at Cadence.
上传时间： 2013-11-19
上传用户：m62383408
数字与模拟电路设计技巧IC与LSI的功能大幅提升使得高压电路与电力电路除外，几乎所有的电路都是由半导体组件所构成，虽然半导体组件高速、高频化时会有EMI的困扰，不过为了充分发挥半导体组件应有的性能，电路板设计与封装技术仍具有决定性的影响。 模拟与数字技术的融合由于IC与LSI半导体本身的高速化，同时为了使机器达到正常动作的目的，因此技术上的跨越竞争越来越激烈。虽然构成系统的电路未必有clock设计，但是毫无疑问的是系统的可靠度是建立在电子组件的选用、封装技术、电路设计与成本，以及如何防止噪讯的产生与噪讯外漏等综合考虑。机器小型化、高速化、多功能化使得低频/高频、大功率信号/小功率信号、高输出阻抗/低输出阻抗、大电流/小电流、模拟/数字电路，经常出现在同一个高封装密度电路板，设计者身处如此的环境必需面对前所未有的设计思维挑战，例如高稳定性电路与吵杂(noisy)性电路为邻时，如果未将噪讯入侵高稳定性电路的对策视为设计重点，事后反复的设计变更往往成为无解的梦魇。模拟电路与高速数字电路混合设计也是如此，假设微小模拟信号增幅后再将full scale 5V的模拟信号，利用10bit A/D转换器转换成数字信号，由于分割幅宽祇有4.9mV，因此要正确读取该电压level并非易事，结果造成10bit以上的A/D转换器面临无法顺利运作的窘境。另一典型实例是使用示波器量测某数字电路基板两点相隔10cm的ground电位，理论上ground电位应该是零，然而实际上却可观测到4.9mV数倍甚至数十倍的脉冲噪讯(pulse noise)，如果该电位差是由模拟与数字混合电路的grand所造成的话，要测得4.9 mV的信号根本是不可能的事情，也就是说为了使模拟与数字混合电路顺利动作，必需在封装与电路设计有相对的对策，尤其是数字电路switching时，ground vance noise不会入侵analogue ground的防护对策，同时还需充分检讨各电路产生的电流回路(route)与电流大小，依此结果排除各种可能的干扰因素。以上介绍的实例都是设计模拟与数字混合电路时经常遇到的瓶颈，如果是设计12bit以上A/D转换器时，它的困难度会更加复杂。
上传时间： 2014-02-12
上传用户：wenyuoo
