Active and passive filters are two types of electronic circuits used to filter out unwanted frequencies from signals. They differ in their components and operation:

1. Passive Filters:

   • Passive filters use only passive components such as resistors, capacitors, and inductors to filter signals.
   • They do not require an external power source for operation.
   • Passive filters are typically simpler and less expensive than active filters but may have limitations in terms of frequency response, attenuation, and impedance matching.
   • Common types of passive filters include low-pass filters, high-pass filters, band-pass filters, and band-stop filters.

2. Active Filters:

   • Active filters incorporate active components such as operational amplifiers (op-amps) in addition to passive components.
   • They require an external power source for operation.
   • Active filters offer advantages such as higher gain, improved selectivity, and better control over filter characteristics compared to passive filters.
   • Active filters are more complex and may be more expensive to implement, but they offer greater flexibility and performance.
   • Common types of active filters include active low-pass filters, active high-pass filters, active band-pass filters, and active band-stop filters.

Types of Passive Filters:

1. Low-Pass Filter: Allows frequencies below a certain cutoff frequency to pass through while attenuating higher frequencies.
2. High-Pass Filter: Allows frequencies above a certain cutoff frequency to pass through while attenuating lower frequencies.
3. Band-Pass Filter: Passes a range of frequencies between two cutoff frequencies while attenuating frequencies outside this range.
4. Band-Stop Filter (Notch Filter): Attenuates a specific range of frequencies while passing frequencies above and below this range.

Types of Active Filters:

1. Active Low-Pass Filter: Similar to a passive low-pass filter but with an operational amplifier (op-amp) used for gain and buffering.
2. Active High-Pass Filter: Similar to a passive high-pass filter but with an operational amplifier (op-amp) used for gain and buffering.
3. Active Band-Pass Filter: Similar to a passive band-pass filter but with an operational amplifier (op-amp) used for gain and buffering.
4. Active Band-Stop Filter (Notch Filter): Similar to a passive band-stop filter but with an operational amplifier (op-amp) used for gain and buffering.

In summary, passive filters use only passive components and do not require an external power source, while active filters incorporate active components like operational amplifiers and require an external power source. Both types of filters are used in electronic circuits for various applications such as signal conditioning, audio processing, and communications.