Electronics > Beginners
Purpose of this amplifier circuit with op. amplifiers
Yansi:
So stacking two nasty opamps one after another, makes for a better amp? What a nonsense. The combined response will likely be even worse, not better (apart from the open loop gain, which will likely rise and make it with less phase margin - i.e. less stable).
Or did I miss something?
vealmike:
--- Quote from: Yansi on February 04, 2019, 11:10:18 am ---So stacking two nasty opamps one after another, makes for a better amp? What a nonsense. The combined response will likely be even worse, not better (apart from the open loop gain, which will likely rise and make it with less phase margin - i.e. less stable).
Or did I miss something?
--- End quote ---
Gain bandwidth product is a constant. Theoretically cascading two amps would increase this.
ogden:
--- Quote from: Yansi on February 04, 2019, 11:10:18 am ---So stacking two nasty opamps one after another, makes for a better amp? What a nonsense. The combined response will likely be even worse, not better
Or did I miss something?
--- End quote ---
Yes indeed.
https://www.eevblog.com/2014/01/25/eevblog-572-cascading-opamps-for-increased-bandwidth/
Zero999:
--- Quote from: ogden on February 04, 2019, 12:08:07 pm ---
--- Quote from: Yansi on February 04, 2019, 11:10:18 am ---So stacking two nasty opamps one after another, makes for a better amp? What a nonsense. The combined response will likely be even worse, not better
Or did I miss something?
--- End quote ---
Yes indeed.
https://www.eevblog.com/2014/01/25/eevblog-572-cascading-opamps-for-increased-bandwidth/
--- End quote ---
Doing it with two op-amps within the same feedback loop isn't a good idea though, as it increases the risk of oscillation. The usual way to do it is to have two separate amplifiers in series, each with the square root of the required gain. For example, if you require a total gain of 100, use two amplifiers, each with a gain of √100 = 10, in series, giving a total gain of 100.
Yansi:
Stacking multiple stages with low gains each makes sense. Stacking them directly like will improve close to nothing, just raise problems with stability.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version