*Question E7C05:
Which filter type has ripple in the passband and a sharp cutoff?*  

*Correct Answer is  D: A Chebyshev filter*  

### AI Response: (may contain errors)  

To determine which filter type has ripple in the passband and a sharp cutoff, let's analyze the options:

### Correct Answer: D: A Chebyshev filter

- **Chebyshev Filter Characteristics**:
  - This filter type is designed to have a steeper roll-off compared to a Butterworth filter, which means it can achieve a sharper cutoff.
  - It exhibits ripple in the passband, which is a defining characteristic. This ripple allows for the sharper transition between the passband and the stopband.

### Why the Other Choices are Incorrect:

- **A: A Butterworth filter**:
  - The Butterworth filter is known for its maximally flat frequency response in the passband, meaning it has no ripple. It provides a smooth response but does not have a sharp cutoff compared to Chebyshev filters.

- **B: An active LC filter**:
  - Active LC filters can be designed to have various characteristics, but they do not inherently have ripple in the passband. The response depends on the specific design and components used, but they typically aim for a flat passband.

- **C: A passive op-amp filter**:
  - Passive filters do not use active components like op-amps. While op-amp filters can be designed to have specific characteristics, a passive filter (which does not include op-amps) cannot have ripple in the passband. Additionally, passive filters generally have a gentler roll-off.

### Summary:
- **Chebyshev filters** are the only type among the options that have both ripple in the passband and a sharp cutoff. 
- Remember that the trade-off for the sharper cutoff is the ripple in the passband, which is a key feature of Chebyshev filters.

This understanding will help you identify filter types and their characteristics in the Extra Class exam.