ative filter design

[sarjan88]

Design a circuit using op-amp that will reject the 60kHz power line noise and also reject high signal frequency above 800Khz. The stop-band width around the 60kHz centre frequency is 10kHz. Use a cascade of 1st order high pass and 1st order low pass filter to implement this circuit. The voltage gain at passband frequencies is 10.

As mentioned in the title, can sum1 tell me this should be a band reject or band pass filter?
i try to construct a band reject filter but the result seem like not correct.

here is my circuit using multisim
[IMG]http://i325.photobucket.com/album…
here is the result using AC analysis in decibel
[IMG]http://i325.photobucket.com/album…

can sum1 help me out of this?
thanks

[pebe]

I think the question is a contradiction in terms.

The first sentence implies a passband filter rolling off at 60kHz and 800kHz. The required use of a 1st order low pass filter and a 1st order high pass filter confirms that because there would a 6dB/octave roll-off, and the required voltage gain of the passband is given as 10.

But it mentions the bandwidth of the 60kHz stop-band frequency as being 10kHz. If the 60kHz is on the skirt of the passband it won't have a bandwidth. That could only apply if there was a notch at 60kHz. But if the two 1st order filters are intended to make a stop band filter, rather than a pass band one, it would require more filter elements to filter out signals above 800kHz.

I think you should go back to whoever raised the question to get clarification.

BTW, I cannot see your circuits.

[sarjan88]

http://i325.photobucket.com/albums/k392 ... ircuit.jpg
http://i325.photobucket.com/albums/k392 ... result.jpg
sorry...here is the image,
i also feel like the question have some problem, if it need a stop band at 60khz and stop at 800khz mean i need 2 low pass and a high pass is it?
first low pass stop at around 55khz then another lowpass combine with high pass make a band pass....aw..thx for your help

[Gus B]

Design a circuit using op-amp that will reject the 60kHz power line noise and also reject high signal frequency above 800Khz.

60KHz power line noise? Did you mean 60Hz?