# All Questions

92 questions
31 views

### Differential amplifier CMMR, NON-IDEAL Op-Amp used

I have a little trouble with the analysis of a differential amplifier. What I want to do is to determine the CMRR of the whole amplifier taking into consideration the CMRR of the op amp. This is the ...
74 views

### How to analysis this Operational-Amplifier circuit?

This is a reference buffer circuit that make a single-end audio input to be the differential inputs for ADC. Circuit-1: It does not like typical Op-Amp circuit of the same purpose like below. ...
257 views

### Voltage output waveform of a differentiating amplifier

I have the following picture of the input and output voltage waveforms from a differentiating amplifier as shown below: And the schematic is as shown below: My teacher claimed that these waveforms ...
28 views

### What causes the necessity for a bias resistor for floating differential mode inputs?

Following excerpt from a text says Figure a and Figure b are equivalent: But in practice when Figure b is used we are recommended to use a 10k or upto 100k resistor between the inverting terminal and ...
41 views

### Finding Vout and Gain of a differential amplifier

I am given this figure below: And I am trying to find Vout and the gain. From looking at this source: https://www.electronics-tutorials.ws/opamp/opamp_5.html I have determined the gain to be 10k/1k ...
45 views

### Differential (Subtractor) op amp with low pass filter

is it possible to have a subtractor circuit with a low pass filter in it? My thought is that I would have the possibility of doing that if I add a capacitor in parallel with R3. Is it actually ...
85 views

### BJT differential amplifier: What causes common mode voltage gain?

In any normal op amp, if it was ideal it would have a gain such that the output voltage would be However in reality this is not the case as there is a common mode voltage gain and hence in reality ...
80 views

### Ideal Op Amp Circuit

I have a question about the circuit below. I want to find Vo in terms of Vi. But I don't fully understand the principles about an ideal op amp's output. You will see my questions in bold at the bottom ...
87 views

### Differential Amplifier with TLC272 vs TL082

I have an LM2576-adj configured to step down 12V regulated output from a wall wart to around 5V-ish (see schematic). On the 5V output I have a 0.1 ohm sensing resistor (Rsc) to measure the output ...
91 views

### Which load resistance is connected to generator U2?

I have this op amp and one of the questions says Which load resistance is connected to generator U2? This is my attempt but I can not confirm if it right. No it's not homework, it examples I'm ...
63 views

### Mathematical model for differential signals and relation with reality

i have a question and i hope is not that strange. i spend some time asking myself how people came out with the mathematical model for differential signals and why is this better in this way?! to be ...
517 views

### Virtual Short Concept in an Op-Amp

By virtue of the open-loop gain being infinity for an ideal op-amp, the two input terminals are said to be virtually shorted. Yet, the virtual short concept is only applied to op-amps in negative ...
100 views

### Need to convert unbalanced to differential input OPAMP

I have the following filter after the DAC chip (currently with unbalanced outputs) working very well, but I need now to change the DAC chip. The new source has differential outputs. Is there a ...
52 views

### Can one voltage output from OpAmp read with two ADC inputs?

this might be a little silly question, but please advise me. I am trying to use two photodiodes (one for the absorbance measurement and one for the source of the light as a reference) and the voltage ...
93 views

### Gain problem of inverting opamp

I'm implementing the circuit in the schematic on the breadboard. Difference of inputs V1 and V2 is about 5mV. Differential opamp has gain of 17,4 Inverting opamp has gain of 26 First problem: I ...
87 views

### Is there such a thing as a fully differential line driver?

I'm looking to find something similar to the TI drv134 (http://www.ti.com/lit/ds/symlink/drv134.pdf), but then with differential inputs instead of single ended. Is there even such a thing? I can't ...
71 views

### Differential gain of an op-amp and feedback

In an op-amp, we know from basic electronic courses that vo = A(v1 - v2) Assuming large differential gain and finite output, we get that (v1-v2) is very very small, ideally zero. In a university ...
70 views

### How to measure external voltage differential with single ended ADC?

I would like to measure voltages from external circuits with the single ended ADC from an Atmega324. The plan is to power the Atmega324 with 3.3V and use a 1.024 or 2.048 voltage reference. The ...
111 views

### OPAMP - Current sense - unexpected behavior

I want to trigger an interrupt on an ATMEGA328P, when the current of a load is below a certain value. Therefore I designed the following differential amp circuit using an LM358 Below picture shows ...
1k views

### Comprehension problems with op-amps

The common differential amplifier takes two signals and amplifies the difference between these two signals. I am aware that this difference usually is around a few millivolts or microvolts so, to put ...
153 views

### Fully differential amplifier - adder?

I have two signal sources providing the same differential audio signal (VIN1 and VIN2). I want to sum those signals. The result (VOUT) shall also be differential. The idea is to take a fully-...
78 views

### Differential Op-Amp rising and falling error at zero [closed]

So I have a differential OP-AMP I've designed is essentially a cut and paste of the circuit seen below. simulate this circuit – Schematic created using CircuitLab I'm using it to track the ...
602 views

### Strange Behaviour Using LM358 Op-Amp as Wheatstone Bridge Difference Ampliflier

I've been working on building a circuit which uses a wheatstone bridge to find the value of a resistance temperature sensor (Danfoss AKS 21) and then passes that to a differential amplifier the output ...
289 views

### Differential op amp to measure negative current flow through shunt (Rails set to 0 and 5v)

Note* I have done some searching and though there are related topics to this one, this one is unique and I think it warrants its own Question, especially as asking additional questions on another ...
3k views

### Review request: DIY DC to 50MHz differential oscilloscope probe

Given the cost of proper differential probes, i've decided to make my own. The requirements are: DC to 50 MHz 3db bandwidth A few selectable input voltage ranges, from 3V pk-pk to 300 V pk-pk ...
131 views

### Need help with instrumentation amp behaviour

I was wondering if someone could help me understand why this instrumentation amp isn't working the way I think it should. The amp is an INA155. My intention is that at if a voltage (positive or ...
287 views

### Issue with bipolar to unipolar opamp circuit

i want to measure ac voltage.For that i need to shift an ac differential voltage (+1.23/-1.23 across R20) to 0v - 2.5v range for a unipolar adc.The R1,R21,R22 divides the voltage and gives +/-1.23v ...
257 views

### Offsetting a differential amplifier to remove the need for a dual supply

I'm developing two similar circuits that will enable me to differentiate the X and Y coordinates from a segmented photo-diode (Four segments). These coordinates will be dependent upon the position of ...
385 views

### How to apply 180 degrees out of phase signal at inputs of differential amplifier in laboratory when only one function generator is provided in lab?

In this differential operation experiment, two input AC signals have to be applied to the bases such that they are 180 degrees out of phase with each other, but I am not sure how to invert an AC ...
35 views

### Modelling this differential ended system for SPICE simulations and grounds

Considering above illustration, imagine a voltage measurement by a voltmeter where the voltage is coming from a differential output device i.e a device which sends mirrored voltages according to its ...
75 views

### Multiple differential amplifier

I have a small problem. I want to design a "multiple differential amplifier". With this, I mean a circuit that, given the inputs and outputs: simulate this circuit – Schematic created using ...
3k views

### Understanding the necessity of Tail Current Source in Differential Amplifier/Simulation (SPICE)

My objective is to understand the need of the tail current source in a differential amplifier. So, to understand the significance of current source, I tried simulating the behavior with and without ...
161 views

### THS4521-HT: Op-Amp giving negative differential voltage

Can someone help to explain where I get wrong with this schematics? I use a differential op-amp THS4521 and want to measure the differential signal coming from a pressure sensor (transducer). The ...
544 views

### Remove DC offset from differential output, rotary encoder

Op-amp in my circuit is accepting differential sinusoidal signal, that swings around 0 V with 1 Vpp. It is configured as a comparator - swings to upper rail when the signal is positive and swing to ...
271 views

### Trans-impedance Amplifer with a Fully-Differential Amplifier

I'm designing a trans-impedance amplifier (TIA) for a fairly fast Avalanche Photodiode (APD), to amplify pulses of 1mA that last few nanosecond. I found a solution that have just enough bandwidth with ...
43 views

### Variable differential amplifier

I made this scheme: simulate this circuit – Schematic created using CircuitLab Gain of this differential amplifier is constant and equal to 2. I would like to have possibility to substract ...
394 views

### What if you alter a differential amplifier by giving it a positive feedback rather than a negative feedback?

Figure 1 In the above Image 1, you see is a differential amplifier . It has a negative feedback as required. Now take a look at figure 2 below. Figure 2 Lets take a look at figure 2. Now that I ...
213 views

### Using ADS1252 In DIfferential mode

I am trying to use ADS1252 ADC with Arduino. I got following schematic from git of a breakout board for ADS1252 Now there is only one pin dedicated to input signal whereas I want to use this board ...
96 views

### Amplifier output goes haywire with load attached

I'm trying to create an op amp using FETs and BJTs. I need the gain to be over 500, currently without a load attached I have the gain about 1000. The input is a 0.05V sine wave, the output is ...
404 views

### What mathematical equation can be used to represent the output of this differential amp circuit?

My lecturer has gave my class a number of circuits to analysis and currently I'm having trouble with the following circuit: I am familiar with how to calculate an equation for the standard ...
42 views

### Differential Op Amp queston

So we are given the equation: Vout=Rf/Rs(V2-V1) I'm just wondering how would we solve it when the Rf/Rs are different values like they are in this circuit: simulate this circuit – Schematic ...
251 views

### Is there an amplifier voltage limit for the input signal even if the differential voltage is small?

I am building a simple current sensor. The amp says the maximum differential voltage is 5V. I'm not getting more than 1V in differential voltage at the moment. Is it safe to test differential ...
485 views

### Difference Amplifier with 3 Op. Amp. How to analyze it?

I have to demonstrate, in the following circuit, that $V_o= \left( 1+\frac{2R_2}{R1}\right)(V_2-V_1)$ if the Pot is in the halfway. I know that the circuit inside the pink block its a Buffer for ...
532 views

### Sallen-Key with fully-differential output — options?

I have a single-ended audio signal that I want to low-pass filter and convert to differential (with GND as the OCM voltage — that is, when one output is X Volts, the other output shall be −...
287 views

### Efficiency of obtaining differential signalling from a single-ended manufactured transducers

This will be a conceptual question. I'm sometimes dealing with data-acquisition of transducers, like strain gauges, accelerometers ect. sort of sensors. Most of these sensors have their own precision ...
1k views

### Amplifying an audio signal with an op amp

I'm trying to build a pretty basic color organ, but i ran into a problem and I can't seem to find the solution to my specific problem. I built this circuit (using a 3.5mm jack connected to a phone or ...
357 views

### Can I just use one end of a differential op-amp ? (ie use differential op-amp as a single ended op-amp)

I found this awesome op-amp I can use which is super cheap and super fast (NE592D). Unfortunately, it has differential inputs and outputs. I can probably deal with the differential inputs, but how ...
121 views

### Circuit for connecting externally power instrument to MCU

I have externally powered instruments that I need connected to the ADC inputs of an MCU. They output 0-5V analog, and the MCU accepts 0-3.33V. There is no guarantee of the voltage difference in ...