What is the purpose of Cap&Res in Voltage follower

[kumarghz]

Hi,
I have came across a Voltage Follower with Cap & Res at the output (as you can seen in the picture below).
What is the purpose of this Cap&Res? If this is a filter, I guess they has to be connected to ground.
Please advice.



thanks
Kumar

 

[barry]

Hmmm, not quite sure what that is. It's SORT of a voltage follower, but with a high impedance. And some filtering.

 

[keith1200rs]

I would have thought for driving capacitive loads https://www.analog.com/library/analogdialogue/archives/31-2/appleng.html Don't be fooled by the schematic in the Analog Devices link - they have mistakenly swapped the +/- inputs in the last diagram!

Keith

 

[Venkadesh_M]

Hi according to this circuit surely it will be a voltage follower when no load but when applying load the capacitor will come into operation.....

 

[crutschow]

Whatever that circuit capacitor is supposed to do, I don't think it does:-?. According to my simulations, the capacitor has no significant effect on the circuit response, with or without a load.

 

[PA4TIM]

Re: What is the purpose of Cap&Res in Voltage follower

It is very common to place such a cap but it schematic is somewhat strange drawn. This makes that higher frequencys are not as much amplified as low frequency and prevents oscillation.

 

[albbg]

Not sure, but I think is a voltage follower in which the resistor helps to drive capacitive loads, preventing instability and the capacitor in the feedback network further improves the stability creating a pole to suppress high frequency oscillations.

 

[Venkadesh_M]

Whatever that circuit capacitor is supposed to do, I don't think it does:-?. According to my simulations the capacitor has no significant effect on the circuit response, with or without a load.

Yeah may be, because the output terminal is solidly connected with the inverting input, so whatever in the non inverting input will be at final output.. But the changes will be in capacitor voltage.........

 

[kumarghz]

Hello Guys,
I'm very much appreciate to all the explanations your have given to me.

thanks

regards,
M.Kumar

 

[hyleeinhit]

Oscillation may happen when the voltage follower is loaded with a capacitor because of phase delay resulting from the load capacitor. R1 and C1 turn the voltage follower load into R1 in high frequency region.