Offset voltage in op-amps (Amplifiers #8)
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- Опубліковано 7 лис 2023
- There's a pin called OFFSET. What's it for? Why is it important for op-amps to have an adjustment for the offset voltage? Let's design some circuits that correct for the offset error.
Aaron Danner is a professor in the Department of Electrical and Computer Engineering at the National University of Singapore.
danner.group
Video filmed and edited by Cheryl Lim.
@randomcheryl
Given how important amplification is electronics, this video and others like it should be required for all EE students.
Thank you 👏. You made me remember a lot of things that I learned at school years ago and forgot because I didn't use them.
These are really educational, but I was really hoping you'd release the next video in your 10 - Oscillators series.
Those are the most interesting ones!
Great job in explaining. Keep it up. Thank you.
Thank you professor, that was very helpful
Chopper op-amps are another way to remedy the offset problem. But only for slow signals.
sir you have explained it very well , thank you
Given that almost no modern opamps include offset null pins and even many you'd want to use are in dual packages which also has no offset functionality, it'd be nice to include some other designs for fixing offset "externally". Every time I see this problem taught about, it's always only in relation to a single opamp that includes those pins whereas I'd find in most practical cases other design considerations mean I can never use such an 'old' opamp with the 'academic' fix available.
One common way, which is described in many application notes, is to inject a small current into the op amp through a variable resistor in the feedback loop. So basically this equates the use of offset null pins.
Thank you sir 🙏
I have a preamp and buffer to design for an audio preamplifier,the choice was for a TL072,but realistically two TL071s would be better,giving better component placement.
The offset null components would add to the real estate use i have and to be honest i need as much space as is possible due to the main amplifying devices being vacuum tubes,heat constraints and EMI,there are smps boost,voltage inverter,smps buck circuits so space needs to be thought out carefully wasting as little as possible.
Then i thought the TL071 ics should be fine leaving offset null alone,i'll be running them on +-10Vdc regulated from 12Vdc after the inverter the negative will be just over 11Vdc,so regulated to 10Vdc for a signal window of 20pk(10vpk-pk) more than enough for a preamp to avoid clipping.
Any offset dc and people need to understand the offset controls dc leakage at the opamp output,will be blocked by a dc blocking cap input and output.
As for dc bias shifts due to offset the signal window is large and i see no problems in any bias shifts,this is for guitar and without any specialised equipment to monitor the signal i doubt anyone would know.
The TL072 has no function to null the dc offset and there is no reason why two TL072 ics could not be used instead anyway,both are 8 pin dip or soic so8.
Were i designing a piece of medical equipment or a radio telescope then i'd use the offset control but for a mid to low fidelity audio amplifier i see no issues.
I just have to regularly convince myself of this.
How we can fix offset voltage in single supply op amp circuits?
Single supply does not matter. Check out the CA3140 op amp. Can be used in any way.