為了滿足現代高速通信中頻率快速轉換的需求，基于坐標旋轉數字計算（CORDIC，Coordinate Rotation Digital Computer）算法完成正交直接數字頻率合成（ODDFS，Orthogonal Direct Digital Frequency Synthesizer）電路設計方案。采用MATLAB和Xilinx System Generator開發工具搭建電路的系統模型，通過現場可編程門陣列（FPGA，Field Programmable Gate Array）完成電路的寄存器傳輸級（RTL，Register Transfer Level）驗證，仿真結果表明電路設計具有很高的有效性和可行性。
上傳時間： 2013-11-09
上傳用戶：hfnishi
微弱信號檢測裝置 四川理工學院 劉鵬飛、梁天德、曾學明 摘要： 本設計以TI的Launch Pad為核心板，采用鎖相放大技術設計并制作了一套微弱信號檢測裝置，用以檢測在強噪聲背景下已知頻率微弱正弦波信號的幅度值，并在液晶屏上數字顯示出所測信號相應的幅度值。實驗結果顯示其抗干擾能力強，測量精度高。 關鍵詞：強噪聲；微弱信號；鎖相放大；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 隨著現代科學技術的發展，在科研與生產過程中人們越來越需要從復雜高強度的噪聲中檢測出有用的微弱信號，因此對微弱信號的檢測成為當前科研的熱點。微弱信號并不意味著信號幅度小，而是指被噪聲淹沒的信號，“微弱”也僅是相對于噪聲而言的。只有在有效抑制噪聲的條件下有選擇的放大微弱信號的幅度，才能提取出有用信號。微弱信號檢測技術的應用相當廣泛，在生物醫學、光學、電學、材料科學等相關領域顯得愈發重要。 2、方案論證 針對微弱信號的檢測的方法有很多，比如濾波法、取樣積分器、鎖相放大器等。下面就針對這幾種方法做一簡要說明。 方案一：濾波法。 在大部分的檢測儀器中都要用到濾波方法對模擬信號進行一定的處理，例如隔離直流分量，改善信號波形，防止離散化時的波形混疊，克服噪聲的不利影響，提高信噪比等。常用的噪聲濾波器有：帶通、帶阻、高通、低通等。但是濾波方法檢測信號不能用于信號頻譜與噪聲頻譜重疊的情況，有其局限性。雖然可以對濾波器的通頻帶進行調節，但其噪聲抑制能力有限，同時其準確性與穩定性將大打折扣。
上傳時間： 2013-11-04
上傳用戶：lty6899826
Abstract: This application note describes a new generation of digital-input Class D audio amplifiers that achieve high PSRRperformance, comparable to traditional analog Class D amplifiers. More importantly, these digital-input Class D amplifiersprovide additional benefits of reduced power, complexity, noise, and system cost.
上傳時間： 2013-12-20
上傳用戶：JIUSHICHEN
針對傳統的雙線性插值法在對圖像進行插值后會不可避免的產生邊緣模糊的問題，提出了一種改進的線性插值法，該算法首先把待插值點分為三類，然后分別選取合適的已知點進行插值。通過對經典圖像lena和pepper進行插值的實驗結果表明，該算法的插值效果與雙立方法相當，但計算量遠遠小于雙立方，能有效的保持圖像邊緣信息，提高了圖像質量。
上傳時間： 2014-01-17
上傳用戶：杏簾在望
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.
上傳時間： 2013-11-13
上傳用戶：dysyase
The MAX17600–MAX17605 devices are high-speedMOSFET drivers capable of sinking /sourcing 4A peakcurrents. The devices have various inverting and noninvertingpart options that provide greater flexibility incontrolling the MOSFET. The devices have internal logiccircuitry that prevents shoot-through during output-statchanges. The logic inputs are protected against voltagespikes up to +14V, regardless of VDD voltage. Propagationdelay time is minimized and matched between the dualchannels. The devices have very fast switching time,combined with short propagation delays (12ns typ),making them ideal for high-frequency circuits. Thedevices operate from a +4V to +14V single powersupply and typically consume 1mA of supply current.The MAX17600/MAX17601 have standard TTLinput logic levels, while the MAX17603 /MAX17604/MAX17605 have CMOS-like high-noise margin (HNM)input logic levels. The MAX17600/MAX17603 are dualinverting input drivers, the MAX17601/MAX17604 aredual noninverting input drivers, and the MAX17602 /MAX17605 devices have one noninverting and oneinverting input. These devices are provided with enablepins (ENA, ENB) for better control of driver operation.
上傳時間： 2013-12-20
上傳用戶：zhangxin
Abstract: If sensitive analog systems are run from one supply without the sufficient bypassing to eliminate noise,
上傳時間： 2013-11-23
上傳用戶：qiulin1010
Abstract: Specifications such as noise, effective number of bits (ENOB), effective resolution, and noise-free resolution inlarge part define how accurate an ADC really is. Consequently, understanding the performance metrics related to noise isone of the most difficult aspects of transitioning from a SAR to a delta-sigma ADC. With the current demand for higherresolution, designers must develop a better understanding of ADC noise, ENOB, effective resolution, and signal-to-noiseratio (SNR). This application note helps that understanding.
上傳時間： 2013-10-16
上傳用戶：x18010875091
Abstract: Transimpedance amplifiers (TIAs) are widely used to translate the current output of sensors like photodiode-to-voltagesignals, since several circuits and instruments can only accept voltage input. An operational amplifier with a feedback resistor fromoutput to the inverting input is the most straightforward implementation of such a TIA. However, even this simple TIA circuit requirescareful trade-offs among noise gain, offset voltage, bandwidth, and stability. Clearly stability in a TIA is essential for good, reliableperformance. This application note explains the empirical calculations for assessing stability and then shows how to fine-tune theselection of the feedback phase-compensation capacitor.
標簽： Transimpedance Stabilize Amplifier Your
上傳時間： 2013-11-13
上傳用戶：daoyue
Photodiodes can be broken into two categories: largearea photodiodes with their attendant high capacitance(30pF to 3000pF) and smaller area photodiodes withrelatively low capacitance (10pF or less). For optimalsignal-to-noise performance, a transimpedance amplifi erconsisting of an inverting op amp and a feedback resistoris most commonly used to convert the photodiode currentinto voltage. In low noise amplifi er design, large areaphotodiode amplifi ers require more attention to reducingop amp input voltage noise, while small area photodiodeamplifi ers require more attention to reducing op amp inputcurrent noise and parasitic capacitances.
上傳時間： 2013-10-28
上傳用戶：hanbeidang
