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i haven't solve this op-amp questions

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orhanli1

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i have problems about op-amps please help me immediately.

Thanks for your helps

i attached the problems

 

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sunil_n

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hi,

i think it is a band Pass (BP) filter as the first op-amp is a low-pass filter and the second op-amp looks like a high-pass filter.In between freqency will pass through making it a band-pass filter. not sure about the 2nd circuit though.
 

LvW

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hi,
i think it is a band Pass (BP) filter as the first op-amp is a low-pass filter and the second op-amp looks like a high-pass filter.In between freqency will pass through making it a band-pass filter. not sure about the 2nd circuit though.
Just the opposite is true:
* The first stage is a high pass (High frequencies can pass the series capacitors and low frequencies cannot)
* The 2nd stage is a low pass (high frequencies are attenuated (a) in the grounded cap and (b) due to the negative and capacitive feedback ).

---------- Post added at 13:08 ---------- Previous post was at 13:05 ----------

However, the combination equals a good and reasonable bandpass only in case the highpass corner frequency is lower than the corner of the lowpass.
Since no element values are given, the question cannot be answered finally.
 
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sunil_n

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thanks for the information.
Yes it can act as a band-pass or band-stop filter. depends on the cut-off frequencies of both the high and low pass filters
 

orhanli1

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i think the first is second order high pass and the second is second order low pass but ican't be sure
 

LvW

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i think the first is second order high pass and the second is second order low pass but ican't be sure

Why not? Did you read my explanation? Anything wrong with that?
If you like I can give you a more detailed explanation based on feedback theory.
 

orhanli1

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Just the opposite is true:
* The first stage is a high pass (High frequencies can pass the series capacitors and low frequencies cannot)
* The 2nd stage is a low pass (high frequencies are attenuated (a) in the grounded cap and (b) due to the negative and capacitive feedback ).

---------- Post added at 13:08 ---------- Previous post was at 13:05 ----------

However, the combination equals a good and reasonable bandpass only in case the highpass corner frequency is lower than the corner of the lowpass.
Since no element values are given, the question cannot be answered finally.

thaks a lot this is the solution that i wait for.

Thanks other friends.

and i have another question what kind of filter is this too



---------- Post added at 15:29 ---------- Previous post was at 15:22 ----------

i know it is a bandpass too.we use the follower for not-changiNG Transfer function am i true?
 

LvW

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Yes, of course. It's a simple L-C-R bandpass; the follower makes the filter independent on load conditions.
 

orhanli1

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thanks for all informations
 

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