An op-amp (operational amplifier) is a high gain analog voltage amplifier with differential high impedance inputs, and a low impedance output. A basic building block in signal processing, like as amplifier or active filter.

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90 views

Operational Amplifier is not working

I'm trying to use a operational amplifier (INA2126), so I put 10V in vcc, -10V in vss, 0V in reference. The sense pin is connected to the output pin. But the output voltage is always 9.56V, even when ...
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2answers
36 views

Is Multisim simulating right?

I am new to Operational Amplifiers and I am trying to simulate a differential amplifier with a gain of 1.2, here it is: As you can see I am using input voltages higher than VCC and according to ...
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2answers
64 views

Integrator circuit

After applying square wave as input to integrator circuit,I did not got a triangular wave as output.It was like capacitor's charging and discharging curve.What is the reason of not getting a pure ...
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3answers
39 views

Deriving the formula of oscillation frequency for the Phase Shift Oscillator

My aim is to find the oscillation frequency of a Phase Shift Oscillator. I start by finding transfer function of the cascaded RC network. $$ V_o(s) = \dfrac{\dfrac{1}{C_3s}}{R_3+\dfrac{1}{C_3s}} ...
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1answer
40 views

How do you calculate the random input referred offset of a basic two-stage op-amp?

I have all the mismatch parameters necessary, just wondering where to start. Most documentations I see just teach you how to measure, not calculate.
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5answers
94 views

Given an Op Amp where the output voltage is fed back into the negative terminal, why is the gain one? [duplicate]

Apparently, the gain of this Op Amp is one, but I can't see how I could figure that out. Can someone help?
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2answers
74 views

Saturated Transimpedance Amplifier Issue

I am using a transimpedance amplifier with a BP104 Silicon PIN photodiode to receive incoming pulses from an infrared LED with a frequency around 100 kHz. Here is the relevant part of my schematic: ...
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4answers
125 views

Operational Amplifier Virtual ground

I know that an op-amp tries to hold the input voltages the same. So, for virtual ground we can connect + node to the ground and we're getting a 0V on the ...
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3answers
116 views

What does the “phase margin” parameter of an opamp imply?

I was reading datasheet of MCP6072. I saw a parameter namely "phase margin" (table 1-2, page 4). As far as I know, "phase margin" is a control engineering term, and implies the phase difference ...
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0answers
38 views

How to deal with asymmetrical slew rate in 2-stage op-amp?

I made sure to take slew rate into account when designing this op-amp, but the slew-rate appears to be asymmetrical, as apparently the fall time is much slower than the rise time. How do I rectify ...
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2answers
65 views

How to choose optimum length for op-amp design?

I've heard that minimum length is discouraged in analog design due to matching problem but what's the drawback of using very long transistors apart from the size and resistance? Based on the ...
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2answers
111 views

How this circuit works?

Recently, i see such a circuit in a board schematic, but can't figure out how it works, why the first Op Amp has positive feedback ???? Thanks. Question, again, now i complete the circuit with ...
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1answer
37 views

Any good resource for MOSFET op-amp design? [closed]

I've been trying to design a two-stage op-amp for a week, but I haven't been progressing much. Does anyone know good resources that teach you how to design an op-amp (transistor level), preferably ...
2
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1answer
63 views

How do you calculate ICMR?

Let's say the Vdsat = 0.2V for M1 to M4, but 0.5V for M5. VT is 0.5. I think it's: ...
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2answers
155 views

What's wrong with an opamp as a voltage regulator?

I was watching a video about power supply design and it was mentioned that an opamp being used as a regulator like this: simulate this circuit – Schematic created using CircuitLab in ...
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2answers
71 views

How can I pull an op-amp output low without transients?

I am designing a simple 'junk box parts' adjustable constant-current dummy load. The following schematic seems to be the most promising design, where R4 and R3 are part of a current adjust ...
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1answer
68 views

What determines the operating point of an op-amp?

Let's say I have the following 2-stage op-amp: The DC transfer is as such: I would like the slope to be steeper and the center point to be at 0mV input. What should I be changing? In other ...
4
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5answers
211 views

High Voltage differential Measurement

Suppose I want to measure individual cell voltage of a 12-serial-cell battery pack, what would be my most economical options? Single cell voltage is 3V-4.2V but the stack can be between 2-12 cells ...
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1answer
53 views

Precision rectifier using a low-power single supply rail to rail op amp

Rectifying a very low voltage signal turns out to be very hard. (for me) I've tried this a few different ways without good results. I'm looking for a reasonable simple solution that performs well ...
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3answers
193 views

Operational Amplifier Adder

Please explane me why OPAMP is used in the adder circuit? why i can't add voltage without opamp? Anyway current doesn't go into opamp so it goes trought RF resistor ...
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2answers
43 views

Manual shows different settling time for an amplifier than its datasheet?

This transducer manual claims INA110 amplifier has 20 microseconds settling time: http://www.ohtegiken.co.jp/wp/wp-content/uploads/manual_zoc33man_1007.pdf But when I check the data sheet for the ...
2
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1answer
111 views

Unknown circuit symbol (“10 NP”)

I'm trying to figure out what the following schematic symbol is: I'm referring to the "10 NP" with the two vertical bars.
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1answer
99 views

Schematic notation for decoupling capacitor?

I'm wondering where this capacitor should be placed. Is it a decoupling capacitor? There are two supply rails on this particular op-amp, so I'm assuming that this indicates I need to put one between ...
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1answer
47 views

Distortion sine waveform from LT1227 amplifier

Schematic for the amplifier: Before connect it to amplifier circuit: Why the sine wave will distorted? any possible reason? is this due to noise? blue is the input signal of an amplifier and green ...
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2answers
70 views

Rail-To-Rail Comparator Design

I'm trying to detect small current pulses (~1.5mA). Currently I'm generating a ~20mV pulse on a sense resistor and feeding that to the input of an opAmp with some hysteresis. I'm having a bit of ...
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1answer
70 views

Circuit to provide 0-5 V output proportional to 0-30 A from C.T?

I want to design a circuit to protect oveload current of 30A.I have a controller board(PLC) which accepts the voltage range of 0-5 as an input and C.T with 1:7000 turns which can maesure 0.5 -60 ...
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1answer
133 views

Biasing a Non-inverting Amplifier

A signal that swings between -1V and +1V must be amplified with a gain of 2 using MCP602 and then biased by +2.5V, so it eventually swings between 0.5V and 4.5V. The amplifier only connected to 5V, ...
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1answer
52 views

High-current monitoring circuit

I have the following circuitry: Battery Supply => Current Monitoring Circuitry => DC Motors Battery Supply: 4AA NiMH batteries - 4*1.2V (1.5mAh * 4) Current Monitoring Circuitry: Max 4378 chip ...
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3answers
106 views

LM358 output voltage non-zero even though input is zero [closed]

I tried this experiment with LM358 and LM741. I used the circuit mentioned from this question: I have not connected any input source. But I am getting an output of 7.5V. I used R1 as 130 Ohm and R2 ...
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0answers
29 views

OPAMP common mode half circuit with its gain

I have a really complex circuit as shown: M4,M7,M14,M15 all pmos the others->nmos I am asked to draw common/differential mode half circuit. What I don't know: How to deal with M14, M15? Which ...
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2answers
74 views

Op Amp Decoupling with a Virtual Ground

I'm designing a low-frequency op. amp. circuit that operates from a single 10V supply. I'm using a TLE2426 "rail-splitter" to generate a virtual ground, 5V above earth ground, which is used as a ...
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0answers
40 views

Circuit to fix the amplitude of the sine wave

Does anyone have any idea on how to stabilize the various input amplitude of the sine wave for example 1.3V,0.8V to 1V of frequencies between 0 to 10Mhz? I known that a variable gain amplifier can ...
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0answers
57 views

100kHz active filter design

I am designing a basic 100kHz active bandpass filter using opamps (LF353). I am only interested in receiving the 100kHz frequency (might drift a few kHz) from my input signal. I have used a basic ...
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0answers
84 views

RF amplifier, why cascade two amp doesn't work?

I am currently working on a amplifier circuit on 8Mhz signal (around -40dbm). The amplifier is based on a IC chip (lm7171 bin). The problem is, the amplifier works perfectly for individually ...
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1answer
56 views

SMPS --> TDA8920 | +V GND -V op-amp

I'm thinking about buying a TDA8920 audio amplifier and power supply and I need some help buying the right PSU. See edit below. So here's what I know. L (AC) = Live (Brown*) N (AC) = Neutral (Blue*) ...
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3answers
60 views

Inverting Amplifier Not Giving Gain of -2.2

A LM358N op amp is used with R_f = 220k and R_i = 100k, which should give a gain of -2.2 in ...
2
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2answers
103 views

Choosing between active opamp filtering or an LC filter

This question follows a previous one I asked, where I accidentally achieved undesirable results from an opamp. Since then I have read up on active opamp filters (here and here) and refreshed my ...
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1answer
40 views

Comparator: What is appropriate for comparing ranges of about 50-100 mVs? Can I use an LM741 op amp?

I am attempting to create a high voltage signal when the voltage from a sensor I am using drops below a certain threshold, which will be between .05 and .1 Volts. I was trying to use an LM741 op amp ...
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1answer
92 views

Op-amp, Finding the V0

I have to calculate Vo in this circuit. Unfortunately I am very confuse how to do that. I know the current pass I(2ohm)= 0 and ix=0. I choose 5Vx as a super node and because ix=0 then the whole ...
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1answer
113 views

Choosing resistor values for Op-amp and inverting/non-inverting configuration

A LM358AN op-amp is choosen to amplify a AC input signal by a gain of 2.0. The input signal ranges from -1V to +1V and from 0 mA to 16.7 mA. The amplified signal ...
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2answers
99 views

Is it possible to run a photodiode plus op amp on a 3V battery?

Naive question here. I've been toying around with the idea of making a simple light meter. From what I've read, photodiodes generally offer the best sensitivity and accuracy (as compared to ...
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0answers
63 views

Gate resistor needed for this circuit?

I'm making a simple circuit for driving a fan based on temperature. Given that the LM339 needs a pull up (R5) do I need to put a series resistor in between the LM339 output and the gate of the ...
0
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1answer
59 views

Power opamp 'floating' output

So I had to design an amplifier with a 'floating' output. (I don't know if floating is the right word, it's the direct translation from dutch.) See the picture below ( I drew it whilst sitting in the ...
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0answers
55 views

Why does this voltage error amplifier output always reach its saturation voltage?

Why does the voltage output of both amplifier (Vm1 and Vm2 as shown in picture) always reach its saturation voltage?
2
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1answer
104 views

Amplifying and Reading a 0-1 V signal into Arduino

I'm trying to read the (0~1V) output of a current transformer (CT) into the 10-bit ADC input of an Arduino Nano. The CT is sensing the L wire carrying 120V at 60Hz. ...
1
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1answer
74 views

How are the gain and corner frequencies calculated for this speech bandpass filter?

This speech bandpass filter circuit appears in the TI OPA344 datasheet. It says "G = 100" and passband is 300 Hz to 3 kHz. How is the gain and corner frequencies calculated from the various ...
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2answers
115 views

Why does my opamp circuit give only x10 overall gain

I designed the circuit below after a suggestion that I use two gain stages rather than one large stage with an expensive opamp. This help keep the cost of my circuit down (the same application has ...
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2answers
88 views

Single supply 5V low noise hydrophone preamplifier [closed]

The title speaks for itself, I want to know if there is some circuit that provides low-noise, single supply operating at 5V and high gain to be used as a hydrophone preamplifier. The output of the ...
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1answer
108 views

Hardware of amplifier circuit

Output result of the circuit I have connected the circuit in hardware, but how come the output is like this?
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3answers
316 views

Can anyone explain this circuit to me?

I'm looking to generate a differential signal to control a laser projector's galvos, and as I understand it needs to be +5V/-5V (10Vpp). I've found this circuit for a laser harp, but I'm confused ...