Question

Find out the incorrect statement about active and passive filters.

(a) Gain is not attenuated in active filter

(b) Passive filters are less expensive

(c) Active filter does not cause loading of source

(d) Passive filters are difficult to tune or adjust

The question was posed to me during an online exam.

I want to ask this question from Active Filters in division Active Filters of Linear Integrated Circuits

Answer 1

The incorrect statement about active and passive filters is:

(c) Active filter does not cause loading of source

Explanation:

• Active filters use operational amplifiers and other active components, and in some cases, they can cause loading of the source due to their input impedance and power requirements. Although they are typically designed with high input impedance to minimize loading, they can still introduce some degree of loading if not properly designed.

Correctness of the other statements:

• (a) Gain is not attenuated in active filter: This is correct. Active filters can provide gain, which is a key advantage over passive filters, which can only attenuate signals.
• (b) Passive filters are less expensive: This is correct. Passive filters generally use components like resistors, capacitors, and inductors, which are typically less expensive than active components (like operational amplifiers).
• (d) Passive filters are difficult to tune or adjust: This is correct. Tuning passive filters, especially those using inductors, can be challenging. Active filters, on the other hand, are often easier to adjust and provide more flexibility.

Thus, the incorrect statement is (c).