A tutorial on SAR type A/D converters, this note contains detailed information on several 12-bit circuits. Comparator, clocking, and preamplifier designs are discussed. A final circuit gives a 12-bit conversion in 1.8µs. Appended sections explain the basic SAR technique and explore D/A considerations.
上傳時間： 2014-01-21
上傳用戶：釣鰲牧馬
This application note describes a Linear Technology "Half-Flash" A/D converter, the LTC1099, being connected to a 256 element line scan photodiode array. This technology adapts itself to handheld (i.e., low power) bar code readers, as well as high resolution automated machine inspection applications..
上傳時間： 2013-11-21
上傳用戶：lchjng
Highlights the LTC1062 as a lowpass filter in a phase lock loop. Describes how the loop's bandwidth can be increased and the VCO output jitter reduced when the LTC1062 is the loop filter. Compares it with a passive RC loop filter. Also discussed is the use of LTC1062 as simple bandpass and bandstop filter.
上傳時間： 2013-10-24
上傳用戶：chens000
Application considerations and circuits for the LT1001 and LT1002 single and dual precision amplifiers are illustrated in a number of circuits, including strain gauge signal conditioners, linearized platinum RTD circuits, an ultra precision dead zone circuit for motor servos and other examples.
上傳時間： 2013-10-18
上傳用戶：dreamboy36
Differential Nonlinearity: Ideally, any two adjacent digitalcodes correspond to output analog voltages that are exactlyone LSB apart. Differential non-linearity is a measure of theworst case deviation from the ideal 1 LSB step. For example,a DAC with a 1.5 LSB output change for a 1 LSB digital codechange exhibits 1⁄2 LSB differential non-linearity. Differentialnon-linearity may be expressed in fractional bits or as a percentageof full scale. A differential non-linearity greater than1 LSB will lead to a non-monotonic transfer function in aDAC.Gain Error (Full Scale Error): The difference between theoutput voltage (or current) with full scale input code and theideal voltage (or current) that should exist with a full scale inputcode.Gain Temperature Coefficient (Full Scale TemperatureCoefficient): Change in gain error divided by change in temperature.Usually expressed in parts per million per degreeCelsius (ppm/°C).Integral Nonlinearity (Linearity Error): Worst case deviationfrom the line between the endpoints (zero and full scale).Can be expressed as a percentage of full scale or in fractionof an LSB.LSB (Lease-Significant Bit): In a binary coded system thisis the bit that carries the smallest value or weight. Its value isthe full scale voltage (or current) divided by 2n, where n is theresolution of the converter.Monotonicity: A monotonic function has a slope whose signdoes not change. A monotonic DAC has an output thatchanges in the same direction (or remains constant) for eachincrease in the input code. the converse is true for decreasing codes.
標簽： Converters Defini DAC
上傳時間： 2013-10-30
上傳用戶：stvnash
2-1 何謂測量放大電路？對其基本要求是什么？ 在測量控制系統中，用來放大傳感器輸出的微弱電壓，電流或電荷信號的放大電路稱為測量放大電路，亦稱儀用放大電路。對其基本要求是：①輸入阻抗應與傳感器輸出阻抗相匹配；②一定的放大倍數和穩定的增益；③低噪聲；④低的輸入失調電壓和輸入失調電流以及低的漂移；⑤足夠的帶寬和轉換速率（無畸變的放大瞬態信號）；⑥高輸入共模范圍（如達幾百伏）和高共模抑制比；⑦可調的閉環增益；⑧線性好、精度高；⑨成本低。 2-2 圖2-2a所示斬波穩零放大電路中，為什么采用高、低頻兩個通道，即R3、C3組成的高頻通道和調制、解調、交流放大器組成的低頻通道？ 采用高頻通道是為了使斬波穩零放大電路能在較寬的頻率范圍內工作，而采用低頻通道則能對微弱的直流或緩慢變化的信號進行低漂移和高精度的放大。 2-3 請參照圖2-3，根據手冊中LF347和CD4066的連接圖（即引腳圖），將集成運算放大器LF347和集成模擬開關CD4066接成自動調零放大電路。 LF347和CD4066接成的自動調零放大電路如圖X2-1。
標簽： 信號放大電路
上傳時間： 2013-10-09
上傳用戶：ysjing
高速數字系統設計下載pdf:High-Speed Digital SystemDesign—A Handbook ofInterconnect Theory and DesignPracticesStephen H. HallGarrett W. HallJames A. McCallA Wiley-Interscience Publication JOHN WILEY & SONS, INC.New York • Chichester • Weinheim • Brisbane • Singapore • TorontoCopyright © 2000 by John Wiley & Sons, Inc.speeddigital systems at the platform level. The book walks the reader through everyrequired concept, from basic transmission line theory to digital timing analysis, high-speedmeasurement techniques, as well as many other topics. In doing so, a unique balancebetween theory and practical applications is achieved that will allow the reader not only tounderstand the nature of the problem, but also provide practical guidance to the solution.The level of theoretical understanding is such that the reader will be equipped to see beyondthe immediate practical application and solve problems not contained within these pages.Much of the information in this book has not been needed in past digital designs but isabsolutely necessary today. Most of the information covered here is not covered in standardcollege curricula, at least not in its focus on digital design, which is arguably one of the mostsignificant industries in electrical engineering.The focus of this book is on the design of robust high-volume, high-speed digital productssuch as computer systems, with particular attention paid to computer busses. However, thetheory presented is applicable to any high-speed digital system. All of the techniquescovered in this book have been applied in industry to actual digital products that have beensuccessfully produced and sold in high volume.Practicing engineers and graduate and undergraduate students who have completed basicelectromagnetic or microwave design classes are equipped to fully comprehend the theorypresented in this book. At a practical level, however, basic circuit theory is all thebackground required to apply the formulas in this book.
上傳時間： 2013-10-26
上傳用戶：縹緲
鋁電解電容器：詳細介紹原理，應用，使用技巧 電容器(capacitor)在音響組件中被廣泛運用，濾波、反交連、高頻補償、直流回授...隨處可見。但若依功能及制造材料、制造方法細分，那可不是一朝一夕能說得明白。所以縮小范圍，本文只談電解電容，而且只談電源平滑濾波用的鋁質電解電容。 每臺音響機器都要吃電源─除了被動式前級，既然需要供電，那就少不了「濾波」這個動作。不要和我爭，采用電池供電當然無必要電源平滑濾波。但電池充電電路也有整流及濾波，故濾波電容器還是會存在。 我們現在習用的濾波電容，正式的名稱應是：鋁箔干式電解電容器。就我的觀察，除加拿大Sonic Frontiers真空管前級，曾在高壓穩壓線路中選用PP塑料電容做濾波外，其它機種一概都是采用鋁箔干式電解電容；因此網友有必要對它多做了解。 面對電源穩壓線路中擔任電源平滑濾波的電容器，你首先想到的會是什幺？─容量？耐壓？電容器的封裝外皮上一定有容量標示，那是指靜電容量；也一定有耐壓標示，那是指工作電壓或額定電壓。 工作電壓(working voltage)簡稱WV，為絕對安全值；若是surge voltage(簡稱SV或Vs)，就是涌浪電壓或崩潰電壓;，超過這個電壓值就保證此電容會被浪淹死─小心電容會爆！根據國際IEC 384-4規定，低于315V時，Vs=1.15×Vr，高于315V時，Vs=1.1×Vr。Vs是涌浪電壓，Vr是額定電壓(rated voltage)。
上傳時間： 2013-12-23
上傳用戶：gundan
磁珠由氧磁體組成，電感由磁心和線圈組成，磁珠把交流信號轉化為熱能，電感把交流存儲起來，緩慢的釋放出去。 磁珠對高頻信號才有較大阻礙作用，一般規格有100歐/100mMHZ ,它在低頻時電阻比電感小得多。電感的等效電阻可有Z=2X3.14xf 來求得。 鐵氧體磁珠 (Ferrite Bead) 是目前應用發展很快的一種抗干擾元件，廉價、易用，濾除高頻噪聲效果顯著。 在電路中只要導線穿過它即可（我用的都是象普通電阻模樣的，導線已穿過并膠合，也有表面貼裝的形式，但很少見到賣的）。當導線中電流穿過時，鐵氧體對低頻電流幾乎沒有什么阻抗，而對較高頻率的電流會產生較大衰減作用。高頻電流在其中以熱量形式散發，其等效電路為一個電感和一個電阻串聯，兩個元件的值都與磁珠的長度成比例。 磁珠種類很多，制造商應提供技術指標說明，特別是磁珠的阻抗與頻率關系的曲線。 有的磁珠上有多個孔洞，用導線穿過可增加元件阻抗（穿過磁珠次數的平方），不過在高頻時所增加的抑制噪聲能力不可能如預期的多，而用多串聯幾個磁珠的辦法會好些。 鐵氧體是磁性材料，會因通過電流過大而產生磁飽和，導磁率急劇下降。大電流濾波應采用結構上專門設計的磁珠，還要注意其散熱措施。 鐵氧體磁珠不僅可用于電源電路中濾除高頻噪聲（可用于直流和交流輸出），還可廣泛應用于其他電路，其體積可以做得很小。特別是在數字電路中，由于脈沖信號含有頻率很高的高次諧波，也是電路高頻輻射的主要根源，所以可在這種場合發揮磁珠的作用。 鐵氧體磁珠還廣泛應用于信號電纜的噪聲濾除。 以常用于電源濾波的HH-1H3216-500為例，其型號各字段含義依次為：HH 是其一個系列，主要用于電源濾波，用于信號線是HB系列；1 表示一個元件封裝了一個磁珠，若為4則是并排封裝四個的；H 表示組成物質，H、C、M為中頻應用（50－200MHz），T低頻應用（<50MHz），S高頻應用（>200MHz）；3216 封裝尺寸，長3.2mm，寬1.6mm，即1206封裝；500 阻抗（一般為100MHz時），50 ohm。 其產品參數主要有三項：阻抗[Z]@100MHz (ohm) : Typical 50, Minimum 37;直流電阻DC Resistance (m ohm): Maximum 20;額定電流Rated Current (mA): 2500. 磁珠有很高的電阻率和磁導率， 他等效于電阻和電感串聯， 但電阻值和電感值都隨頻率變化。 他比普通的電感有更好的高頻濾波特性，在高頻時呈現阻性，所以能在相當寬的頻率范圍內保持較高的阻抗，從而提高調頻濾波效果。 磁珠主要用于高頻隔離，抑制差模噪聲等。
標簽： 電感
上傳時間： 2013-11-05
上傳用戶：貓愛薛定諤
提出了一種改進的基于直接頻率合成技術（DDS）的任意波形發生器在現場可編程門陣列（FPGA）上的實現方法。首先將三角波、正弦波、方波和升/降鋸齒波的波形數據寫入片外存儲器，當調用時再將相應的數據移入FPGA的片上RAM，取代分區塊的將所有類型波形數據同時存儲在片上RAM中的傳統方法；再利用正弦波和三角波的波形在4個象限的對稱性以及鋸齒波的線性特性，通過硬件反相器對波形數據和尋址地址值進行處理，實現了以1/4的數據量還原出精度不變的模擬信號，從而將整體的存儲量減小為原始設計方案的5%。經驗證，這種改進方法正確可行，能夠大大降低開發成本。
上傳時間： 2013-12-25
上傳用戶：日光微瀾
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