Instrumentation op-amp problem

In summary, the conversation is about a problem with part e) and f) of a homework question related to the common-mode rejection ratio (CMRR) and the transfer function of an instrumentation amplifier. The CMRR is defined as the ratio of the differential gain (Av) to the common-mode gain (Acm). The Acm is equal to the difference between the tolerance of the resistor (Δ) and the resistance (R) multiplied by 2. The first part of the conversation focuses on calculating the Acm and CMRR for part c) and d) of the question. Then, the conversation moves on to discussing part e) and f), where the Acm and Av are used to determine the tolerance of the resistors
  • #1
Weaver
70
6

Homework Statement


question.png


Homework Equations


[/B]
CMRR = Av/Acm

Acm= Δ/R , Δ = (2 x Tolerance of Resistor).R

The Attempt at a Solution


I have an issue with part e) and f) but here are all my workings

c) For this part, Acm would be:
10 x10^-3
This makes 2.5mV -> 0.25 uV (which is the same magnitude as 0.22uV)

I am unsure for this part but would the CMRR in this case be 1/10x10^-3 = 10x10^3 ?

d) Av = 1V/42mV = 23.81

e) Using this model of the instrumentation amplifier

instrumentatoin_amp.png


Acm = 23.8/(10 x10^3) = 2.4 x 10^-3

=> 0.12 % tolerance, which is closest to 0.1% tolerance

Using Rb = 9k and Ra = 100K, which get Av = 23.2

One part I am not sure of is picking the 5V power supply. The only justification I can see, is that no clipping would occur on the output?

f)I'm really not sure of this part, but one possible reason is, it doesn't fix any problems. There is still the broadband noise on the signal, which will be amplified now too and an instrumentation op-amp will still have to be used to get the mic signal
 

Attachments

  • question.png
    question.png
    29.4 KB · Views: 673
  • instrumentatoin_amp.png
    instrumentatoin_amp.png
    15.1 KB · Views: 429
Physics news on Phys.org

1. What is an instrumentation op-amp?

An instrumentation op-amp, also known as an instrumentation amplifier, is a type of electronic amplifier that is used to amplify very small signals, typically in the range of microvolts to millivolts. It is commonly used in scientific and medical instruments to accurately measure and amplify small signals without introducing noise.

2. How does an instrumentation op-amp work?

An instrumentation op-amp typically consists of three operational amplifiers (op-amps) connected in a specific configuration known as a differential amplifier. This configuration allows for the amplification of the difference between two input signals while rejecting any common-mode signals that may be present. This results in a highly accurate amplification of small signals.

3. What are some common problems encountered with instrumentation op-amps?

Some common problems encountered with instrumentation op-amps include offset voltage, input bias current, and thermal drift. These can all affect the accuracy and precision of the amplified signal and may need to be addressed through calibration or circuit design.

4. How can I troubleshoot an instrumentation op-amp problem?

If you are experiencing issues with an instrumentation op-amp, some steps you can take to troubleshoot the problem include checking for proper power supply connections, verifying that the correct resistors are being used, and using a multimeter to measure the input and output signals. Additionally, checking for any loose connections or damaged components can also help identify the issue.

5. What are some tips for selecting the right instrumentation op-amp for my application?

When selecting an instrumentation op-amp, it is important to consider factors such as input voltage range, gain, offset voltage, and frequency response. It is also important to choose an op-amp with low noise and high precision for accurate signal amplification. It may also be helpful to consult with a knowledgeable engineer or refer to manufacturer datasheets for specific recommendations based on your application's requirements.

Similar threads

How to Calculate the Complex Op Amp in Circuit Diagram
    • Engineering and Comp Sci Homework Help
Replies
8
Views
1K
Any advice to make this Op-Amp temperature controller circuit work?
    • Engineering and Comp Sci Homework Help
Replies
34
Views
2K
Charging a battery and monitoring the current w/ an instrumentation amp
    • Engineering and Comp Sci Homework Help
Replies
7
Views
1K
Engineering Common Mode Rejection Ratio: Instrumentation Amplifier Calculation
    • Engineering and Comp Sci Homework Help
Replies
1
Views
978
Monostable Waveforms: Solutions & Resources
    • Engineering and Comp Sci Homework Help
Replies
3
Views
1K
Op-amp compensation of cascade fudges audio signal oddly
    • Electrical Engineering
Replies
3
Views
804
Op amp and 3-db frequency problem
    • Engineering and Comp Sci Homework Help
Replies
4
Views
2K
Op-amp as a comparator (analog-to-digital conversion)
    • Engineering and Comp Sci Homework Help
Replies
1
Views
2K
Does Wien bridge oscillator have a closed-loop gain?
    • Engineering and Comp Sci Homework Help
Replies
27
Views
5K
Solve Ideal Op Amp Question: KCL & KVL
    • Engineering and Comp Sci Homework Help
Replies
4
Views
3K

Hot Threads

Recent Insights

Back
Top