Operational Amplifier Applications Unit 3 – Low Pass Filter
Exercise 2 – Low Pass Filter Phase/Transient Response
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to determine the phase shift
characteristics and transient response of a low pass filter by analyzing circuit input and output
signals. You will verify your results with an oscilloscope.
DISCUSSION
- Depending on the circuit design, low pass filters have varying phase shift characteristics.
- The type of frequency response, number of poles, and the input frequency determine the
phase shift of the filter. - The transient response of a low pass filter is its ability to react to relatively fast changes of an
input signal. - Transient input signals can produce overshoot, undershoot, and ringing.
- Oscillations above and below the ideal voltage level define ringing. Ringing decreases
progressively until the output voltage settles to an ideal level. The time required for the
ringing to die out is called the settle time. - Damping minimizes overshoot, undershoot, and ringing in low pass filters. Damping severely
delays the circuit response time to the input signal positive and negative transitions.