# معلومات مفيدة عن operatioal amplifier



## scorpion1988 (15 نوفمبر 2008)

*Operational Amplifier (Op-Amp) Basics*

*The op-amp is basically a differential amplifier having a large voltage gain, very high input impedance and low output impedance. The op-amp has a "inverting" or (-) input and "non inverting" or (+) input and a single output. The op-amp is usually powered by a dual polarity power supply in the range of +/- 5 volts to +/- 15 volts. A simple dual polarity power supply is shown in the figure below which can be assembled with two 9 volt batteries. *

*Inverting Amplifier: *

*The op-amp is connected using two resistors RA and RB such that the input signal is applied in series with RA and the output is connected back to the inverting input through RB. The non inverting input is connected to the ground reference or the center tap of the dual polarity power supply. In operation, as the input signal moves positive, the output will move negative and visa versa. The amount of voltage change at the output relative to the input depends on the ratio of the two resistors RA and RB. As the input moves in one direction, the output will move in the opposite direction, so that the voltage at the inverting input remains constant or zero volts in this case. If RA is 1K and RB is 10K and the input is +1 volt then there will be 1 mA of current flowing through RA and the output will have to move to -10 volts to supply the same current through RB and keep the voltage at the inverting input at zero. The voltage gain in this case would be RB/RA or 10K/1K = 10. Note that since the voltage at the inverting input is always zero, the input signal will see a input impedance equal to RA, or 1K in this case. For higher input impedances, both resistor values can be increased. *

​*Non inverting Amplifier: *

*The non inverting amplifier is connected so that the input signal goes directly to the non inverting input (+) and the input resistor RA is grounded. In this configuration, the input impedance as seen by the signal is much greater since the input will be following the applied signal and not held constant by the feedback current. As the signal moves in either direction, the output will follow in phase to maintain the inverting input at the same voltage as the input (+). The voltage gain is always more than 1 and can be worked out from V gain = (1+ RB/RA). *

*Voltage Follower: *

*The voltage follower, also called a buffer, provides high input impedance, a low output impedance, and unity gain. As the input voltage changes, the output and inverting input will change by an equal amount. *

​​
*Figure 1: non inverting, inverting, voltage follower*

​​*Though designs vary between products and manufacturers, all op-amps have basically the same internal structure, which consists of three stages:*

*1. Differential amplifier *

*Input stage — provides low noise amplification, high input impedance, usually a differential output *

*2. Voltage amplifier*

* Provides high voltage gain, a single-pole frequency roll-off, usually single-ended output *

*3. Output amplifier *

*Output stage — provides high current driving capability, low output impedance, current limiting and short circuit protection circuitry *

*
**Summing Amplifier *

​*Figure 2:* *Summing amplifier circuit.*​*A summing amplifier circuit is shown in Figure 2 *

*1. Show that the output signal of the amplifier is *

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​​*2. Build the circuit, and check your prediction experimentally for a gain of 10. *

*3. Measure the input impedance of the amplifier by placing various resistors in series with the source. To measure the impedance of one terminal, drive it with a small signal through a resistor and ground the other. Explain your result. *

*
**Integrator *

​*Figure 3:* Integrator circuit.​*An integrator circuit is shown in Figure 3 *

*1. Show that the output signal of the amplifier is *

​*2. Build the circuit with  k ,  F and use square and sinusoidal wave forms to test the predicted behavior. Also place an  M resistor in parallel with the capacitor. This resistor drains charge to avoid saturation due to very low frequency or DC signals. *



​*Differentiator *

​*Figure 4:* Differentiator circuit.​*A differentiator circuit is shown in Figure 4 *

*1. Show that the output signal of the amplifier is *

​
_2. Build the circuit with __ k_ _, _ _F and use triangle and sinusoidal wave forms to test the predicted behavior_.​ 



*Schmitt Trigger *

​*Figure 5: Schmitt trigger circuit. **and **are relative to ground, or some reference between **and **.*​*A Schmitt trigger circuit is shown in Figure 5 The analysis is not difficult. It is, however, tedious. The , voltage divider sets the rough neighborhood of the trigger thresholds. controls the hysteresis of the switch (the difference between the ``turn on'' and ``turn off'' thresholds). The feedback resistor should be a factor 10-100 larger than the voltage divider resistors. Otherwise, it drags the thresholds apart. *

​​*1. Predict the ``turn on'' and ``turn off'' thresholds for  k ,  k ,  k , and  k . Rather than finding a general expression, it's fine to consider this particular case. For the analysis, assume a maximal output voltage swing of  V. This actually varies with each op amp, but should not be far from the truth. *

*2. Build the circuit, using the resistance values given above. Measure the input thresholds of the trigger and compare with your predictions*



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## ENG_ANOO (23 يناير 2009)

شكرا على المعلومات المفيدة
جزاك الله خيرا


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## محمدالقبالي (24 يناير 2009)

بارك الله على الشرح وهذا كتاب
 *
handbook of operational amplifier
applications
* 
اضافه الى الشرح :56:​

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## saadali (25 يناير 2009)

مشكور جزاك الله الف خير


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## scorpion1988 (25 يناير 2009)

مشكورين على الرد واتمنى ان استفدتوا من المعلومات المتواضعة


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## TEC-BOY (25 يناير 2009)

مشكور اخي علي المعلومات 
لكن اتمني ان يكون شرحك القادم احترافي ومرفق ببعض الصور اتمني لك كل التوفيق


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## therarocky (10 مارس 2009)

مشكوووووووووووور وجزاك الله خير


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## علىزكى (12 مارس 2009)

thanks for this information


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## سفرو (4 أبريل 2009)

جزاك الله خيرا على هذه المعلومات


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## مثنىكاظم (7 أبريل 2009)

شكرآ جزيلآ لك على هذا الموضوع المفيد0


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## blackhorse (7 أبريل 2009)

شكرا اخى الكريم على موضوعك ولكن كان من الافضل دعم الموضوع بالصور كما هو مكتوب بالشرح فيوجد صور ناقصة
شكرا لمجهودك


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## احساس القلم (10 أبريل 2009)

أشكركم على طرح أهم جزء بالأجهزة الطبية لضعف الاشارة الحيوية
الله يوفقكم


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## mmukh (20 مايو 2009)

جزاكم الله عنا ألف خير


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## mnci (16 أغسطس 2009)

amplifier circuit

free ebooks download


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## ولد الشرقيه (16 أغسطس 2009)

مشكووووووووورين على هذا الموضوع الرائع ويعطيكم الف عافيه ودي لو كان فيه مترجم انقلش عربي بس يكون ترجمه هندسيه ياليت لو تفيدوني


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## الطموحة (11 يناير 2010)

*جزاك الله كل الخير*


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## زيزفون85 (23 أبريل 2010)

thanks for u


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## waleedthehero (23 أبريل 2010)

thank for the subject ........and for more about *Operational Amplifier

http://liveconcerns-waleed.blogspot.com/2010/04/operational-amplifier-and-google.html

*


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