When I was trying to find an answer for an optimum capacitor value for entire DC removal of a signal I encountered the following:
In general, DC blocking capacitor shall behave like a short at working frequency. Calculate the reactance in ohms of the DC blocking capacitor for a minimum value at your working frequency: Usually Xc(ohms) = 1/(2×3.14×f×C) shall be less than 2 ohms at working frequency.
If this is true, and lets say I want to completely remove DC of a periodic waveform which has 1kHz fundamental freq.
So if I follow that logic (setting Xc=2 Ohm), C = 1/(2×pi×f×|Xc|) and at 1kHz:
C = 1/(2×pi×1000Hz×2ohm) = 79uF
So I guess I should choose 100 uF
If now my understanding is correct, my question is what should be the upper limit and what would be an example to a bad affect of choosing overlarge cap for DC removal. Say you calculate the blocking cap 100nF but in your circuit you use 100uF. What kind of consequences can that have?
Edit: One of the reason asking this is I always see that decoupling caps around opamps are 100nF. What if I use 100uF instead. I know this is not blocking cap but similar confusion.
Whenever we need a capacitor with capacitance C, what I understand using higher value is not a problem for both decoupling and blocking caps. Is that correct? What determines the upper limits?