Questions tagged [operational-amplifier]
Questions relating to the construction and applications of operational amplifiers, which are DC-coupled, high-gain electronic voltage amplifiers with a differential input and, usually, a single-ended output.
7,626
questions
1
vote
1
answer
38
views
Li-ion battery voltage monitoring
tl;dr How to pick resistor (or component) values to alter the triggering voltage level for the second circuit?
Hello everyone. I have First Person View (FPV) goggles whose battery I lost. But since I ...
- 13
1
vote
0
answers
43
views
Limiting op-amp-as-comparator output voltage (or, how to drive a LED without blowing it up)
I'm trying to add turn indicators to my bicycle, driven by the bicycle dynamo (nominal 6 VAC, but voltage does vary; between 6-12 V in all practical driving conditions). The input voltage is rectified ...
- 93
0
votes
0
answers
40
views
Troubleshooting circuit design for sensor input and desired output range [duplicate]
I designed a circuit to process input from a sensor with a range of -300 mV to 300 mV. The desired output of the circuit is 0 V to 600 mV. To achieve this, I used the op-amp equation Vout = Vin + 0.3 ...
- 69
5
votes
2
answers
288
views
Is a fast op-amp more difficult to stabilize than a slow one?
Suppose I want to make a simple non-inverting amplifier with a bandwidth sufficiently low.
Is it harder to make a stable non-inverting amplifier with a fast op-amp? When I read some documentation on ...
- 2,322
1
vote
2
answers
37
views
Inverting op-amp unexpected voltage shift
I'm trying to create an op-amp circuit that attenuates a 5 V input signal down to a 1 VRMS Vout signal (1.414 V Vout).
I need to shift the output signal by 2.5 V so that it can be fed into a unipolar ...
- 13
0
votes
0
answers
31
views
How can I design a circuit to calculate the square root of the sum of the squares of x(t) and y(t) for input signals x(t) and y(t)? [closed]
How can I design a circuit that takes input signals x(t) and y(t) and produces an output signal z(t) that is equal to the square root of the sum of the squares of x(t) and y(t)? Using Opamps ...
0
votes
2
answers
36
views
Is it possible to stabilize every system with an integrator
I was wondering if it was possible to stabilize every system with an integrator. From my point of view, an integrator can be used for applying a dominant pole strategy.
If I place the pole at very low ...
- 2,322
1
vote
3
answers
90
views
What are the pros and cons for the various photodiode circuit arrangements?
I've been messing around with photodiodes do measure relative light intensity from very low light to very bright conditions. My search for information on photodiodes and the circuits they are ...
- 11
5
votes
5
answers
425
views
Single-supply non-inverting op-amp for summing DC voltages at unity gain
Is it possible to use this single supply, non-inverting, summing op-amp configuration to sum multiple arbitrary DC voltages at unity gain?
I've used the inverting summing op-amp config on bipolar ...
- 88
2
votes
1
answer
62
views
Long Term Drift of IC
I wanted to calculate Long Term Drift of output voltage of an IC and in datasheet the value is given as 60 ppm/√kHr. I dont know what exactly this means as there is square root of kHr. Can anyone pls ...
- 251
0
votes
1
answer
48
views
Converting line-level audio to 5 VDC for relay control
I had an idea to build an audio switching device that automatically switches between two inputs to a single output. My exact application would be to have music playing on a speaker while monitoring a ...
5
votes
3
answers
536
views
Circuit design for converting sensor input to desired output range
As part of my project, I am tasked with designing a circuit that can accurately convert a voltage signal in the range of -300 mV to 300 mV, obtained from a sensor to a voltage signal in the range of 0 ...
- 69
0
votes
0
answers
39
views
How does an automotive Mass Air Flow (MAF) sensor circuit start up?
The transistor needs voltage from the amplifier to turn on, but it can't provide it since the transistor is not allowing current to flow through the bridge transistors.
1
vote
2
answers
115
views
Turning on a transistor if one voltage is higher than another [closed]
I would like transistor Q1 to turn on if V1 > V2 with a maximum tolerance of about 0.5 V.
I want to feed the entire circuit with 5 V. Which operational amplifier do you recommend?
And how should ...
- 211
6
votes
3
answers
371
views
How to evaluate the stability of a full wave precision rectifier
I made a simulation of a full wave precision rectifier but I have some difficulties to evaluate its stability.
I would like to evaluate it stability by a Bode plot because it seems that if the input ...
- 2,322
0
votes
1
answer
60
views
Op amp stability consideration
I would like to have your opinion on this circuit :
The source voltage V12 is a feedback of an other loop hidden. So the operating point of the system is changing.
When the 47 Ohm resistor R1 is ...
- 2,322
-1
votes
1
answer
71
views
Op-amp level shifter to shift 0.33-3.3 V to 0-10 V
I have an input signal ranging from 0.326 V to 3.3 V and I need to amplify and shift it so that the output will swing between 0-10 V. How can I achieve that using an op-amp? I know I could do that ...
- 1
0
votes
0
answers
39
views
A problem about LM310N
I have aquestion about LM310. Forgive me because I am not a native English speaker，I used Google translation.
The internal resistance of my input signal terminal is very large, about gigaohm level, ...
- 1
0
votes
0
answers
17
views
5T OTA Vout in Cadence simulation is always just VDD?
I'm working on an 5T OTA with the following schematic:
Here's the simulation circuit:
I'm using a VDD = 2.5V since the transistors are rated for that in the model library I'm using.
My issue is that ...
- 201
2
votes
2
answers
112
views
10 MΩ resistor needed on op-amp input for correct operation
Circuit:
The 3 kΩ in series with the switch in the circuit represents a metal probe that gets connected to ground when water is present (switch open = no water; switch closed = water).
Due to the ...
- 23
5
votes
6
answers
2k
views
Purpose of 1 kΩ resistor in parallel with load at output of op-amp
As I was reading some op-amp data sheets, I noticed they placed output resistors to ground in some test circuits. These can be seen in the insets of the plots below for the LTC6228 and the LT6202.
...
- 355
2
votes
2
answers
104
views
When is the DC gain error of a single supply op-amp zero?
Suppose I designed a single supply op-amp, with \$V_{dd} = 1.8\mathrm{~V}\$, and \$V_{ss} = 0\mathrm{~V}\$. Furthermore, I designed the op-amp such that \$V_{out,max} = 1.3\mathrm{~V}\$ and \$V_{out,...
- 75
0
votes
0
answers
15
views
LTspice to PSIM
I was trying to construct the circuit of UC3843 on PSIM and stumbled across a useful circuit created in LTspice. Now I am confused about these circuit symbols and what they represent:
At first glance,...
- 11
0
votes
0
answers
20
views
Building an error amplifier according to the given application note [duplicate]
I was building the UC3843 in PSIM from scratch to be used as a current mode control.
This is the block diagram:
However, I am struggling to construct the error amplifier in the circuit. First of all, ...
- 11
0
votes
2
answers
79
views
Class AB Amp slight distortion at any level
I wanted to build an amplifier for a spare set of 4 ohm 20W speakers I have laying around. After three days of searching circuits on the internet and trying them out on a breadboard not having much ...
- 13
0
votes
0
answers
45
views
translating LVDS to LVTTL using amplifier and high speed output buffer
I am receiving an LVDS clock differential signals and need to convert them to LVTTL .
the problem is that the LVDS frequency is above 500Mhz and the LVTTL output needs to drive a 50ohm resistors, when ...
- 21
-1
votes
0
answers
37
views
How to come up with a schematic diagram that includes a laser diode, laser receiver, LM358 signal amplifier, ESP32 board, and LCD screen? [closed]
I am trying to work on a non-invasive glucometer project. I have failed to use most simulators to come up with a schematic diagram since most of them lack laser receivers and the LM358 signal ...
- 1
0
votes
2
answers
67
views
Can I split the channels in a two-channel op-amp?
I have this circuit:
In this circuit, I have two single-channel op-amps.
Can I just make an adapter, splitting one dual-channel op-amp into each section?
0
votes
1
answer
37
views
Building the Error amplifier circuit part of UC3843
I am trying to build an error amplifier circuit on PSIM almost identical to the
In the datasheet, they used
Now, I want to ask in what ways is different than a normal Op-Amp element in PSIM.
...
- 11
0
votes
0
answers
61
views
Converting Balanced Audio to Unbalanced Audio without Damaging Sink
I want to receive a stereo balanced audio signal and feed it into the stereo microphone inputs via my motherboard's header pins.
I added about a 30 dB reduction in gain which looks good on the scope ...
- 453
2
votes
1
answer
65
views
Op-amp overheating - Generating two variable voltages
I have a stereo potentiometer (10 kΩ) and a +5 VDC voltage (regulated by a 7805) with which I am trying to generate two "inverse" voltages, so at the same time one channel being high ...
1
vote
1
answer
52
views
Input resistance of an inverter op-amp circuit
I need to find the input resistance of this circuit. There are two parts of this exercise:
The first one is to find the input resistance of the circuit without the capacitor.
The second is to the ...
- 23
6
votes
3
answers
955
views
What is the purpose of these passives in a microphone pre-amplifier circuit?
This is the typical application circuit of the MAX4466 "microphone preamplifier" op-amp.
Are these resistors/capacitors purely for generating a bias voltage? If so, aren't there much simpler ...
- 81
2
votes
4
answers
110
views
Is RC frequency response related to series RC or parallel RC?
So in playing around with some frequency response stuff I made this circuit:
And I found that the cutoff frequency value is set by the Feedback Resistor and the capacitor. Take note that the ...
- 81
1
vote
2
answers
71
views
Input resistance of an op-amp circuit
I need to find the input resistance of this circuit. There are two parts of this exercise:
The first one is to find the input resistance of the circuit without the capacitor.
The second is to the ...
- 23
1
vote
5
answers
127
views
What is the correct way of amplifying the output of an active filter?
I have been trying hard to implement a narrow band pass filter using operational amplifiers.
Here is the circuit:
So far, I was able to get correct result in spice simulations, but when I put the ...
- 13
-1
votes
1
answer
54
views
How do I create a circuit which has cyclical output?
I am thinking about using some sort of hysteresis comparator circuit to pull of this particular output.
However it is particularly difficult to see what I could do to produce this circuit.
Edit: The y ...
- 1
0
votes
0
answers
90
views
How can I translate LVDS to LVTTL with limitations?
I want to convert LVDS differential signals to LVTTL.
I have 2 limitations:
The frequency of the LVDS signal is around 500 MHz.
The LVTTL voltage output should be around 2.4 V and it needs to drive a ...
- 21
0
votes
0
answers
35
views
auto zeroing in comparator modelling
I am trying to model comparator with offset correction using auto zeroing method. Initially I am trying to model the ideal capacitor in LTspice. Here, I charge the top plate of the capacitor using ...
0
votes
1
answer
29
views
How can I convert a stim signal from analog to digital?
I want to get a digital signal from dstm1,2,3,4, but I can't.
What's the problem?
- 11
0
votes
0
answers
27
views
Implementation of Gain as a Resistance in an Integrator
I am trying to follow along with a thesis project block diagram but I am fundamentally confused as to how they have implemented the circuit.
The above circuit is a delta-sigma modulator but more ...
- 25
0
votes
2
answers
65
views
Building a DC circuit that produces output voltage from 1 to 10 in 1V increments [closed]
I have been trying to design a DC circuit that can produce a range of output voltage from 1 to 10 in 1 voltage increments with just (non-inverting) operational amplifiers, switches, resistors, and ...
- 1
0
votes
1
answer
80
views
LTspice Bode plot is incorrect or inconsistent (op-amp circuit)
I'm testing the open loop transfer function of an op-amp circuit by following this schematic:
This is my LTspice schematic (keep in mind the actual op-amp circuit itself has been thoroughly checked, ...
- 1
1
vote
5
answers
176
views
Usage of input voltages in ideal opamp
Why does the difference between inverting and non-inverting voltages in an ideal opamp be equal to zero in many problems??? I can't seem to realize that. Let's say that if the difference voltage ...
- 21
0
votes
2
answers
51
views
Op-amp current values
In this App note, page 7, example 3, can someone tell me from where the values for IBN and IBI are coming from? I.e.
\$I_{BN}\$ = -(5 nA + 0.5 nA)
\$I_{BI}\$ = (5 nA - 0.5 nA)
I'm using this MCP601 ...
- 3,953
2
votes
3
answers
83
views
Improvement in current sensor accuracy
I want to improve the accuracy of a current sensor. 49% of the error I have at the moment is from the tolerance of the shunt resistor and 26 percent of that it is from the op amp offset voltage.
How ...
- 251
1
vote
1
answer
56
views
How does one choose the overdrive voltages of the transistors in a differential amplifier?
Question
Hi there,
So in the following image taken from Razavi, the part highlighted confuses me. He states the sum of all the overdrive voltages in each cascode branch is equal to 1.5V. Now, is this ...
- 75
0
votes
2
answers
65
views
741 in non inverting - single +5V suppl;y?
I need to amplify a +1mV to +100mV input with a gain of 10.
I was thinking of using a 741 with this circuit
https://www.electronics-tutorials.ws/opamp/opamp_3.html
The specs say it's dual supply, ...
- 129
0
votes
0
answers
57
views
Reading PT1000 using op amp
I am looking for an op-amp circuit that can take in 24 VDC and output 0-10 V. It will be connected to my temperature sensor. I have found one diagram but I believe there should be some changes to it. ...
2
votes
3
answers
82
views
Input common-mode offset voltage ranges of op-amp
I'm using an MCP6V81 op-amp.
While trying to understand, I see that the output of the op-amp can't be greater than Vdd and less than Vss. If that's the case, could someone clarify how the common-mode ...
- 3,953