Hello i am using a Lowpass filter to effectively "create in a sense" a analogue signal. The problem im having is the example that i was shown fourth diagram has a smooth wave essentially. However for mine it has to have an input frequency of 62.5Khz and i have used a lowpass to cutoff half of this (we were told to do this). The problem i have is that i dont understand why for the same circuit with a frequency of 1kHz looks much cleaner than mine of 62.5kHz. Why is this? Is it essentially the same just since the larger frequency makes it look more compact? Essentially im asking is for the input of frequency 62.5kHz will this give me an audio signal? I believe i have done what is correct besides from the output going through an amp (just focusing on the filter stage at the moment). I dont have the equipment to physically test it at the moment either. My main worry is that this (62.5kHz input frequency) output signal doesnt look like a typical analogue, sine shaped signal essentially but however just looks like a lot of noise (diagram 2 red signal). As in also for the enlarged image (diagram 3) from 0 to 1ms, there is no sine shape to it, like the example that was given (diagram4 or like diagram 1?
Shortform: Dont understand why for diagram 2, the output doesnt look like a audio signal such as for example the shape of diagram 1 or 4? Diagram 3 is an enlarged version of diagram 2. Did i do something wrong? I have my high pass filter at cutoff 20Hz and this removes the dc bias and my lowpass at cutoff 62.5/2kHz (as the pwm outputs 62.5kHz, i know a lowpass isnt needed since 62kHz is much larger than the audio heard to humans (i.e. 20-20kHz) but it was stated that it should still be done. Th voltage divider is used due to the output voltage needing to be under a certain voltage due to the amp needing 0.4 to -0.4V. Hence why does my signal change with larger input frequencies and lower frequencies?
I am probing all graphs at the TOP node for C2
Note: Vout is not where i have probed and i know that it is not the actual output voltage for these circuits