please help me design a low pass filter(not an ordinary RC filter) using op-amps. it's urgent...this is for our project which is a voice recorder..the low pass filter is used for the output signal coming from the DAC decoder...the cut-off freq. is 8khz and the supply voltage of the filter circuit must be 5 volts..i really need help...if anyone can give a circuit to me,kindly discuss to me the calculation in obtaining the cut-off freq at 8khz....thanks