I need to implement a low pass filter to convert a 20kHz square wave into a 20kHz sine wave. It would be nice to be able to use lower values, because in CMOS large resistors and capacitors take up huge amounts of space.
Is it possible to reduce the value of RC required to achieve a given cutoff frequency?
This paper suggests that it's possible to hook it up so the cut off frequency is multiplied by the gain, allowing me to use smaller RC values. It states that the low pass filter makes the output of the entire circuit high pass. If I swap RINT and CINT, should this make the entire circuit low pass?
Below is my implementation, the output, and the expected output. I've tried it both ways round.
Is my idea possible, and where did I go wrong? Thanks.