help with Switched-Capacitor filters

[ronybhai]

for the following circuit
the switching frequency fCLK= 50 kHz. For this circuit the cut-off frequency is calculated from: ωc= fCLKC2/Cf , and the mid-band gain is given by Av(mid) = C1/C2 .
Determine appropriate values for the capacitors C1, C2 and Cf to obtain a cut-off frequency of ωc = 500 rad/s, and a mid-band gain of 10.
Please if any one can help me out...really appreciate.
I just had lesson on Switched-capacitor. But didn't get it that much.

these are the things I know ωc=C2/Cf, Av(mid)= 1+Cf/C1
The frequency of a switched-capacitor Integrator is proportional to the clock frequency and depends on C1 and C2. Change the fCLK, we can control the time constant of an integrator.

 

[LvW]

It is not clear what you are asking for.
You are speaking of
* midband gain (applies to a bandpass),
* cut-off frequency,
* integrator,

The circuit diagram shows an S/C lowpass and you write down some formulas.
But - what is your question?

 

[jeffrey samuel]

Do you want to know the value of cap to do what

be more exact in it

 

[ronybhai]

Determine appropriate values for the capacitors C1, C2 and Cf to obtain a cut-off frequency of ωc = 500 rad/s, and a mid-band gain of 10.

 

[LvW]

Determine appropriate values for the capacitors C1, C2 and Cf to obtain a cut-off frequency of ωc = 500 rad/s, and a mid-band gain of 10.

Do you know the meaning of the parameter "mid band gain" you are using? It is a bandpass parameter! Please explain, otherwise no answer is possible.

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By the way - I can imagine what you mean: DC gain (for S/C circuits: gain for very low frequencies). However, I think for designing filters one should be aware of the correct terms (excuse this teaching behaviour).
Regarding the capacitor choice: It is the featured property of S/C circuits that only capacitance RATIOS determine the various properties and parameters. Thus, you can select all values satisfying your design principles (technology, time charging/discharging, parasitic influences,...).

 

[ronybhai]

no dnt knw the mid band gain

 

[LvW]

no dnt knw the mid band gain

ronybhai, you ask for help which may consist of several sentences and formulas.
But - at the same time - you are too lazy to use all 4 letters in four-letter words let alone to ask a clear question.

 

[jeffrey samuel]

with out them there is no point in asking a question here pal

any more inputs from you are more welcome

 

[ronybhai]

ronybhai, you ask for help which may consist of several sentences and formulas.
But - at the same time - you are too lazy to use all 4 letters in four-letter words let alone to ask a clear question.

I didn't get it?
lazy to use what 4 letters?

 

[jeffrey samuel]

no dnt knw the mid band gain

He meant this pal your post was no complete words in them

 

[FvM]

I didn't get it?
lazy to use what 4 letters?

Please take the time to read the general forum rules, particularly what's said about sms abrevations.

 

[ronybhai]

Please take the time to read the general forum rules, particularly what's said about sms abrevations.

Sorry for that...
Kindly if anyone can help with the question or if any one know any kind of information which can help me to get to solution...thanks a lot
I just recently started to learn about switched capacitor. So I am not kind of sure where to start and how?
Thanks a lot for the help and your time.

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Av=C1/C2, C1=10*C2
CF=FCLK*C2/ωc

 

[LvW]

Sorry for that...
Kindly if anyone can help with the question or if any one know any kind of information which can help me to get to solution...thanks a lot
I just recently started to learn about switched capacitor. So I am not kind of sure where to start and how?
Thanks a lot for the help and your time.

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Av=C1/C2, C1=10*C2
CF=FCLK*C2/ωc

What kind of "solution" do you need?
All the formulas you have written down are OK.
However, you should select a ratio Fclk/Fc of at least 100.
This requirement gives you the ratio Cf/C2.