I was trying to visualize what happens when frequency is swept from 1Hz to 1GHz. In case of capacitor, voltage lags behind current by 90 degree and capacitor reactance depends upon it's frequency.
I have tried simulating the RC filter using
LTSpice. The picture is given below but my question is very general and for theoretical understanding.
I want to understand the
phase response of the filter. Since, voltage lags behind the current in capacitor (which is connected in series with voltage source). Therefore, they will be some voltage across capacitor and it's intensity will depend upon the frequency (decreases with increase in frequency). I have tried to understand the RC filter working. I have tried to explain what happens in RC filter when frequency is swept from 1Hz to 1GHz.
- Stop-Band: The frequency will be low and reactance of the capacitor will be very high. All of the voltage will be across capacitor and will be delayed by 90 degrees. The output (voltage across resistance will be nearly zero).
- Transition-Band: The reactance of the capacitor will start to decrease relative to the resistance. The voltage at output (across resistance) will be subtraction of Voltage source's voltage and delayed version of voltage source (90 degree). Therefore, overall phase of the system will be less than 90 degrees.
In this band, reactance of capacitor will be nearly zero and hence, there will be 0 phase delay. Although there will be some voltage across capacitor which will appear as
ripplesin the pass-band.
Is my understanding correct?