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Minimum feedback resistor Rf for given opamp ex: opa2134
i have a problem that needs solving; What is the minimum feedback resistor for modern opamps like opa2134 ? can it be 100 ohm? Im asking because in lt1028 datasheet its says it cant be <100ohm...
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Why feedback resistance is high?
simulate this circuit – Schematic created using CircuitLab In this drain to gain feedback resistance biasing circuit, it is said that the feedback resistance Rg is large and usually in \$M\Omega\$...
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What is the drawback of a high-value resistor for positive comparator...
I'm building a simple circuit which has an LM211 comparator at its heart. The positive input is connected to a 10k-10k resistor divider across the supplies, stabilized by a 1uF capacitor. Hysteresis...
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calculate value for resistor in
I have an LMC6001 op-amp, and I would like to build the ph probe amplifier featured in the datasheet. Unfortunately, I am not sure what R9 is or should be. Does R9 control slew rate? How would I...
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How does this sample and hold circuit work?
What role does the 30k resistor play in the LF398? How would that resistor eliminate any offsets introduced by the op-amps in a circuit like this one: On this explanation, I don't get this line: These...
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How to calculate the feedback resistors for an SMPS
I have designed an SMPS circuit for my host board. As the datasheet, the feedback resistors are calculated as As per the datasheet, Feedback Voltage(Vref) is 0.6V and I want 4V Output Voltage....
View ArticleFind v1 and v2 of a summing amplifier when it is in series with another Op-Amp
There is a summing amplifier with two AC power sources (v1+v2,) each connected to a different Ground. Each of these sources connect to a resistor (R1+R2,) and then to a summing point, which branches...
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Why would you stack a resistor and capacitor on top of each other?
I've inherited an charge amplifier/shaping circuit from my predecessor. When he wanted to make a low-pass filter with current-to-voltage conversion, he had a standard circuit like: simulate this...
View ArticleHow does resistive feedback affect noise figure?
I am working on a design with cascode CS amplifier with resistors in the feedback. What are the advantages and disadvantages of such topology? How the resistors in the feedback affects noise figure?...
View ArticleHow can I create a resistor (rheostat) network adjustable from 10kohm to 1Mohm?
This is for a part of a system that provides feedback to a voltage reference of 0.6 V. The output voltage has a range of 125 V to 500 V. Using a voltage divider, 414k and 2k will provide the 0.6 V...
View ArticleSide effects of using large resistances
Are there any problems that can be caused by using resistors of large resistances (in the order of megaohms)? I'm designing a feedback network that is just a voltage divider, and I want the feedback...
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Buffer OPAMP feedback resistor
I am using an LT1630 as a buffer... I know its not the greatest OPAMP for the job because it has fairly Hi input current, but It has good DC characteristic, HI current drive, and rail to rail...
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Need help choosing resistors for difference amplifier
In the circuit below I am trying to achieve 15.56 gain on IC2. The following combinations (in kOhms) are fairly close: 20/1.3 or 200/13 = 15.38 47/3 or 470/30 = 15.67 51/3.3 or 510/33 = 15.45 56/3.6...
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Op amp with feedback
simulate this circuit – Schematic created using CircuitLab How to calculate Iout(current flowing through RL) of this circuit? All Resistors are of same value except the load resistor. Let the rail...
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I don't understand how the resistor between GND and the source in a...
See this circuit: Applying KVL around the gate-source-GND-gate loop, I get Id = (Vg - Vgs)/Rs. I know the typical argument begins with, if Id increases then Vs increases, but I am not sure of how it...
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Analysing BJT circuit
Recently, I found this circuit on the Talking Electronics web page:I was interested in the modified circuit below, where the feedback capacitor is replaced with short circuit and the 8R speaker with...
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Feedback resistor and capacitor calculation for transimpedance amplifier
I am designing a transimpedance amplifier using LTC6268-10 from Analog Devices. The photodiode that I use is S9055-01 from Hamamatsu and the laser source that I use has a power of 10mW with the...
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Why are resistors and capacitors placed in the feedback network of op-amp...
I've been looking at a circuit that has an amplifier cascade used in a servo amplifier. In this amplifier cascade, there are blocks to control the gain and blocks to control the roll-off frequency of...
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