Questions tagged [operational-amplifier]

Questions relating to the construction and applications of operational amplifiers,

Filter by
Sorted by
Tagged with
1
vote
0answers
13 views

Opamp compensating circuit

While reading a book on opamps I came across this output offset voltage compensating circuit. They used thevenin's circuit looking at Ra from point T: Then they converted a part of the first ...
0
votes
5answers
62 views

LED and Photodiode Data Acquirement System

So I am to develop a project this semester and wanted to be shed some light on certain topics. The goal of the project is the following: Detect a pendulum's period using an LED and a photodiode and it ...
2
votes
3answers
197 views

Is there any relation/leak between two sections of LM358 op-amp?

I want to use section A of LM358 OA to limit the current and section B to convert Arduino PWM to analog, and then connect output B to non-inverting input of input A as reference voltage. The LM358 ...
1
vote
1answer
90 views

Op-Amp unusual symbol

I find this circuit in an old book. Regardless what is the task of this circuit, i wonder why the op amp symbol is unusual(curved)? This is the datasheet of LM301A: http://www.utm.edu/staff/leeb/...
2
votes
3answers
57 views

Generate accurate 20mV Vref

I want to generate 20mV Vref using Op amp, like this: When simulate with TINA using model from TI, instead of 20mV at output (Vref port), i see that it is 27.95mV. My question is: Why I can't get ...
0
votes
0answers
36 views

Designing Mic with integrated preamplifier

I would like to design from scratch a battery powered large diaphragm mic with integrated opamp preamplifier to 3.5mm line out jack for pc. I have two capsules. One from a t.bone sc400 and one RK-47....
0
votes
1answer
32 views

What the R value to this operational amplifier isn't saturated?

In the following circuit, the three ideal operational amplifiers are polarized such that their saturation voltages are ± 20 VDC. The other components of the circuit are resistors, one of them being ...
1
vote
1answer
55 views

Window comparator diode direction

What happens if we reverse the configuration of diode in window comparator? Will it remain a window comparator?
0
votes
2answers
67 views

AGND VS DGND on PCB?

Could someone please tell me the difference between analog ground and digital ground on pcb? It would be easier if you explained it with a example!
0
votes
3answers
73 views

op amp non-inverting input isn't working?

simulate this circuit – Schematic created using CircuitLab Why in above schematic if i left the non-inverting input floating or connected to 1V or 3.3V the LED stays ON and current doesn't ...
0
votes
1answer
31 views

Operational Amplifier and Strain Gauge

My laboratory involves using a strain gauge and an instrumentation amplifier to amplify the signal from the strain gauge. The op amp schematic is shown below: Any assistance with the following ...
-2
votes
1answer
83 views

Constant current LED driver using opamp

I'm trying to design a constant current LED driver and am totally confused! This is the schematic i end up with: simulate this circuit – Schematic created using CircuitLab What's the formula ...
0
votes
2answers
63 views

Replace optoisolator with a resistor

I found this circuit that I wanted to quickly implement. He is using an optoisolator and feeding back the output using it. I understand that the optoisolator is isolating the sensitive circuit from ...
0
votes
3answers
68 views

OP Amp 0-5 VDC Output

I have the circuit pictured below. I need to change the potentiometer from a 20K to a 5K and still get the 0-5 VDC output. VCC = 5V Is this possible? What needs to change to make this possible?...
1
vote
1answer
64 views

Norton Op-Amps advantages

I have been reading about Norton Operational Amplifiers, I get a good idea of how they work, even at the transistor level, I understand that difference current in = voltage output. What I have been ...
6
votes
3answers
150 views

Operational Amplifier with mixed feedback

So, I came across this circuit in a test, it's regarding the operation of an op amp with multiple (positive and negative) feedback, the circuit is as follows: I was asked to evaluate the following ...
4
votes
3answers
178 views

What are the calculations to do in practice to estimate beforehand the noise seen on the output of this op amp circuit?

I would like help with understanding something better, but am not trained in electronics so please bear with me! I am trying to make a simple circuit to take a {-10V ... +10V} signal from a function ...
0
votes
2answers
31 views

Is it good using INA213 to amplify +/- 33mV to range 0 -> 3.3V?

I need measure AC current range 0 - 25A using current transformer and burden resistor, voltage swing from -33mV to +33mV. I searched and found INA213 (datasheet). Can I use 3.3V power supply to INA312 ...
0
votes
1answer
31 views

Gain at Break frequency of OpAmp

I find this formula for an op-amp written in a book: Unity Gain Bandwidth=A*Fo Where, A is the open loop gain of the opamp Fo is the break frequency What I inter from this expression is that the ...
0
votes
1answer
93 views

An ideal op amp is given (with infinity gain), what is the current flowing through all the resistance for the given circuit?

my problem is that do the output terminal of the op-amp behaves like short circuit of output terminal of the op-amp to its reference ground as shown in the ideal op-amp internal circuit?
0
votes
1answer
44 views

Transistor modelling for npn transistor

I am learning about differential amplifiers I found the circuit for AC analysis in a book as shown: They transformed it to a transistor model circuit as shown: Though I am not excellent at circuit ...
-1
votes
0answers
37 views

OPAMP undervoltage detection - Trouble in real life

I've been trying to realize an OPAMP undervoltage protection circuit (see attachment, OPAMP voltage comparator topology). I'm using the AD8032 2.7 V Rail-To-Rail Amplifier for this task. In LTSPICE ...
1
vote
1answer
107 views

Phase margin is 90 degrees but transient step response shows overshoot

The bode plot of the loop is as shown here The transient step response looks like this The block diagram looks something like this - Basically a single stage opamp(OPAMP in fig) with high gain(...
2
votes
1answer
74 views

150V voltage follower

I am working on a datalogger to measure the voltage of a series of solar modules. I have 4 solar modules in series, let say 35V each. I am using an ADS1115 for the measurements. First I wanted to do ...
0
votes
1answer
42 views

Function Generator amplifier to drive resonance circuit help

I have a model resonance circuit that is excited with an auxiliary winding and I need to build an amplifier to be able to amplify the current from the function generator in order to drive the ...
0
votes
0answers
47 views

Current monitor for a High frequency signal

I'm working on a current monitoring circuit for a high frequency current monitoring application as shown in the schematic below, the requirements are as follows. Should be able to provide RMS current ...
0
votes
0answers
35 views

What is the Rseen from this node?

In the text book I am reading (CMOS Analog Circuit Design by Razavi) the author wrote that the Rseen from node N is (1/gm7), however when I derived it myself I found that the Rseen is ro4 // ro6 (...
0
votes
0answers
47 views

Frequency compensation of a two-stages class AB amplifier

The author of the book on which I'm studying explains in depth the following "standard" two-stages op-amp: In order to deal with frequency compensation, he models each stage with a transconductance ...
1
vote
2answers
58 views

Two-stages class AB amplifier

I'm studying the following two-stages class AB amplifier: Basically it is a standard two-stages op-amp (i.e. the cascade of a differential pair with active current mirror followed by an inverter with ...
1
vote
1answer
21 views

XADC Current Sensing Reference Design

Please refer to this reference design for AC701 (snippet below). The schematics, specifically the current sensing sections in pages 34-36, show this: I want to understand why, for the REF output of ...
0
votes
1answer
77 views

Question about the slew rate

Let's consider an op-amp: From basic courses of electronics, we know that the output voltage as a function of the differential input is given by the following picture: Now, assuming that: the op-...
0
votes
0answers
34 views

Calculation of the slew rate of a two-stages op-amp

Let's consider the following two-stages op-amp: I have difficulties in understanding how the author of my book calculates the slew rate of this op-amp. The book says: Question 1: Why should the ...
0
votes
1answer
41 views

Constant current source for an alternating magnetic field of varying frequency and constant amplitude from a solenoid

The project I am working on requires me to oscillate my sensor. I am doing this by coating a ferromagnetic material on the sensor and applying a sinusoidally varying magnetic field. I was applying the ...
0
votes
1answer
52 views

LT1677CN8 alternative?

we are trying to build the K&J Magnetics Seismometer in my physics class and we are having trouble getting the LT1677. It's not available at the moment. What can we substitute in place of the ...
1
vote
1answer
49 views

Definition of the offset voltage for a single-ended op-amp

Let's consider an op-amp: The book I'm reading says that, ideally, if the voltage difference between the two inputs is zero (thus vin1=vin2) then the output voltage should be zero. However, because ...
-2
votes
0answers
44 views

Op amp Amplifier [on hold]

I am trying to figure out how to design a circuit with these parameters and I just having trouble figuring out the circuit.
1
vote
1answer
42 views

measuring ac voltage drop across a resistor with a solenoid in series with it

I wanted to measure the phase difference between the current (magnetic field due to the solenoid) and the system response. I am doing this by measuring the voltage drop across the resistor in series ...
1
vote
1answer
38 views

Voltage Threshold Gate Circuit from 0-5V Input

Background: I have a circuit in which when Vin is applied, the super capacitors have to be charged before anything else in the circuit can be utilized (otherwise I will undervolt the devices I am ...
2
votes
3answers
112 views

Is there a simple way to discharge a bipolar capacitor using a 5V signal and a MOSFET/BJT?

I am using an op amp configured as an integrator, as shown in the schematic below. There is an input signal which can go both positive and negative [+1V ... -1V], and then depending on this input ...
0
votes
2answers
54 views

differential opamp reference

simple model of a diff opamp with an independent differential signal source figure 1 how does current flow through the transistors since V1 and V2 and referenced to each other and not to vee? i ...
2
votes
2answers
230 views

Some questions about a series pass transistor & op amp voltage regulator [on hold]

I have the following voltage regulator using a series pass transistor and an op amp providing the base voltage: I have three questions: How do you calculate the output voltage for such a regulator? ...
0
votes
3answers
43 views

What is an external nulling “resistor”? [duplicate]

in the following datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/OP07.pdf Which is a OP07 a high precision ultralow voltage offset OpAmp, it says in the datasheet. ...
3
votes
1answer
78 views

Analyze op amp circuit

I want to know how to calculate the output of the below op amp. I know this is supposed be an inverting amplifier with offset but I have never seen the connection of the offset to the negative side of ...
0
votes
0answers
27 views

buffer on differential line

Is it advisable to put individual buffer amp on the differential line.Consider the attached scenario? Or for the N part of it shall to the -ve of single Amp? simulate this circuit – Schematic ...
0
votes
1answer
28 views

Current sensing using XADC

AC701 Schematics Refer page 40 of the schematics. Here for Vccint- the regulator is switching at 250 kHz. page 34 has the sensing signal conditioning for that the inst. amp used is INA333 which ...
0
votes
1answer
51 views

Help to determinate stability of Opamp Circuit

I have background in software but this time I need to build a circuit for scaling a signal from 15 to -15 VDC. At college I took some subjects on Electrical topics so I have read to remember, after ...
0
votes
0answers
27 views

What wrong with my Bias AC Voltage by Opamp's circuit, LTSpice?

I need measure AC 230V 50Hz and use transformer current type. Below is my schematic and simulator result. The schematic create by easyEDA, they use LTSpice to simulate circuit. I need signal swing ...
0
votes
2answers
126 views

PNP linear regulator problem

I am designing a linear step-down regulator using a PNP pass transistor. The output of the regulator is good at no load. When I connect my regulator to a battery supply, leave it for 2 seconds and ...
2
votes
1answer
73 views

Question about the common mode

After introducing the two-stages op-amp and frequency compensation for this circuit, during lecture the Professor asked us to find as an exercise a possible polarization of the following circuit: in ...
2
votes
3answers
100 views

Unkown DIP IC (OP277PA)

I stumbled upon the most uncommon thing. An 8-PIN DIP IC with part number (OP277PA.) However, the datasheet is nowhere to be found and I've done my research. Is it possible that it is an OPA277P, or ...