Instrumentation Amplifier with 2 Op Amps Explained
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- Опубліковано 24 сер 2024
- An implementation of a differential-input instrumentation amplifier is discussed in this analog circuit example. This circuit is designed with two Operational Amplifiers and ladder resistor network. The presented analog circuit analysis employs a combination of Op Amp virtual short, Superposition and Kirchhoff Circuit Laws (KCL and KVL) to show that output voltage is equal to an amplified difference of the two input voltages with a gain equal to (1+2/3*alpha) where alpha is defined by the choice of resistor in the circuit. Please see the analog circuit and signal processing videos playlist • Electrical Engineering... for more op amp and analog circuit examples.
An implementation of a differential-input instrumentation amplifier is discussed in this analog circuit example. This circuit is designed with two Operational Amplifiers and ladder resistor network. For more examples please see the analog circuit and signal processing video playlist ua-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
And Digital Circuits and DSP playlist ua-cam.com/play/PLrwXF7N522y6cSKr0FmEPP_zQl011VvLr.html
Thanks for watching.
A interesting addition to 2 op amps "instrumentation" amplifiers family with high impedance inputs. Such architecture has a disadvantage at a low gain: op amps saturate very quickly when common mode voltage is relatively high. Let's say a common mode voltage of 25-30% of a rail voltage already can saturate them when a gain is 6dB. When we increase a gain, everything is fine. So, if we know a purpose and limitations we are good -)
Thanks for watching and sharing your thoughts. The parameter alpha is recommended to be at least >=30 in this circuit that then realizes a differential gain >=21. WIth that in mind, I agree with you that a good designer should run common mode and CMRR analysis to make sure the differential amplifier does not saturate for the target input range. Thanks again 🙂
@@STEMprof You are welcome, Sir. Thanks that you teach us.
@@sc0or My pleasure.
Hi.
Excellent work.
Will this work on a unipolar power supply ?
Like a 5V power rail ?
You are very welcome. Glad that your liked this differential instrumentation amplifier video. For unipolar design, please note that extra care in terms of proper DC biasing of input terminals of Op Amps and then DC decoupling both output signal and applied input signals are required. Note that the resulting output differential signal can be negative or positive depending on whether V2>V1 or V2