Electronics - Operational Amplifiers - Discussion
Discussion Forum : Operational Amplifiers - General Questions (Q.No. 20)
20.
What is the cutoff frequency of this low-pass filter?


Discussion:
24 comments Page 1 of 3.
Vikas said:
1 decade ago
My answer coming 1.8khz
Chiranjit said:
1 decade ago
Can you explain the process?
Sowmya said:
1 decade ago
I'm getting 4.8kHz i.e fc=(1/2*pi*C*R)
Sub values v get 4.822 khz.
Please any one tel me is it correct or not ?
Sub values v get 4.822 khz.
Please any one tel me is it correct or not ?
Mahesh said:
1 decade ago
I too getting 4.8 khz please explain.
Harshith said:
1 decade ago
Please tell me cutoff frequency formula for low pass filter.
Nisha said:
1 decade ago
fc=1/(2*pi*R*C)
= 1/(2*3.14*33*10^3*0.001*10^-6)
= 4.8KHZ
= 1/(2*3.14*33*10^3*0.001*10^-6)
= 4.8KHZ
D sati said:
1 decade ago
At cut off freq output of opamp should be 1/2^.5.
At frequency 0hz output is=vin
So at cutoff freq vout= vin/1.414
Because vout = vin/(r*s*C+1)
Or |v|=vin/((r*s*c)^2+1)^.5
So (r*s*c)^2=1
So r*s*C=1
So 1.8k ans.
At frequency 0hz output is=vin
So at cutoff freq vout= vin/1.414
Because vout = vin/(r*s*C+1)
Or |v|=vin/((r*s*c)^2+1)^.5
So (r*s*c)^2=1
So r*s*C=1
So 1.8k ans.
Ch. Sathish Kumar said:
1 decade ago
Could you please elaborate your answers @D Sati and @Vikas. If we calculate with the formula you gave it again gives the answer as 4.8KHz. And the other thing I would like to put forth before you is that the advantage of this configuration is that the op amps high input impedance prevents excessive loading on the filters output while its low output impedance prevents the filters cutoff frequency point from being affected by changes in the impedance of the load.
Shobha said:
1 decade ago
Take load resistance RL = R = 10K.
Because the formula 1/(2*pi*RL*c).
Because the formula 1/(2*pi*RL*c).
Vignesh said:
1 decade ago
I think 4.8khz is correct answer. Because of LPF cutoff frequency formula is 1/2*pi*R*c.
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