*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)  

A Chebyshev filter is the correct answer because it is designed to have ripple in the passband and a sharp cutoff. Here's why:

1. **Chebyshev Filter**:
   - **Ripple in the Passband**: Chebyshev filters are characterized by having an equiripple behavior in the passband. This means that the amplitude response oscillates between a maximum and minimum value, creating a ripple effect.
   - **Sharp Cutoff**: They have a steeper roll-off compared to Butterworth filters, which means they transition more quickly from passband to stopband. This makes them useful when a sharp cutoff is needed.

2. **Why the Other Choices are Incorrect**:
   - **A: Butterworth Filter**: 
     - Butterworth filters have a maximally flat response in the passband, meaning there is no ripple. They provide a smooth response but do not have as sharp a cutoff as Chebyshev filters.
   - **B: An Active LC Filter**:
     - This is a general category of filters that can be designed to have various characteristics, including Butterworth or Chebyshev responses. The term "active LC filter" does not specify ripple or cutoff characteristics.
   - **C: A Passive Op-Amp Filter**:
     - Similar to active LC filters, passive op-amp filters can be designed with different characteristics. The term itself does not imply ripple in the passband or a sharp cutoff.

In summary, the Chebyshev filter is specifically known for its ripple in the passband and sharp cutoff, making it the correct choice for this question.