opamp question

Thread Starter

nithin ravindran

Joined Jul 2, 2010
2
Why is the gain so important when its feature is to rectify?
because we need a symmetrical waveform at the output. if the -ve half cycle of the i/p wave is amplified more by the equation 1+(Rf/R1), how can we get a symmetrical waveform? the above situation occurs when -ve half cycle gets inverted by 1st opamp and then passed by lower diode and then amplified by 2nd opamp. my question is what is the eqn for the gain in this 2nd stage? whether it is 1+(Rf/R1)?
 

Ron H

Joined Apr 14, 2005
7,063
because we need a symmetrical waveform at the output. if the -ve half cycle of the i/p wave is amplified more by the equation 1+(Rf/R1), how can we get a symmetrical waveform? the above situation occurs when -ve half cycle gets inverted by 1st opamp and then passed by lower diode and then amplified by 2nd opamp. my question is what is the eqn for the gain in this 2nd stage? whether it is 1+(Rf/R1)?
The gain of the second stage depends on whether the input is positive or negative.
See the equation and explanation on the schematic I posted.
 
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