High-Pass Filter
Low-Pass Filter
Numerical Low-Pass Filter
High-Pass RC Filter:
-
![](highpass.png)
- Capacitor passes high frequencies, blocks low
frequencies
- In frequency domain, capacitor impedance,
Z(ω)=1/jωc
- So, the impulse response,
![](highpass_h.png)
- where,
![](highpass_wc.png)
- Whose magnitude,
![](highpass_g.png)
- And phase,
![](highpass_phi.png)
- So that,
![](highpass_xfer.png)
- G is easiest viewed on a Bode (log-log) plot:
![](highpass_gplot.png)
- Φ is 0° for high frequencies, 90° at low
frequencies, and 45° at the -3dB point:
![](highpass_phiplot.png)
- Note: The affect of a high-pass filter can be numerically
undone with the droop correction algorithm.
- Low-Pass
RC Filter:
Capacitor
passes high frequencies, blocks low frequencies
- In frequency domain, capacitor impedance,
Z(ω)=1/jωc
- So, the impulse response,
![](lowpass_h.png)
- where,
![](highpass_wc.png)
- Whose magnitude,
![](lowpass_g.png)
- And phase,
![](lowpass_phi.png)
- So that,
![](lowpass_xfer.png)
- G is easiest viewed on a Bode (log-log)
plot:
![](lowpass_gplot.png)
- Φ is 0° for high frequencies, 90° at low
frequencies, and 45° at the -3dB point:
![](lowpass_phiplot.png)
Copyright © Raymond Allen
2006-2021