5.4.3 Types offilters Many electrical filters are active devices based on op-amp technology. Passive filters have very low noise, require no power supplies, and have a wide dynamic range: Active filters are much more adjustable and versatile, can cover very wide frequency ranges, have very high input and very low output impedances, and can be configured for simple switching from low-pass to high-pass and combination for band-pass or band-reject behavior5.4.3 Types of filters Many electrical filters are active devices based on op-amp technology. Passive filters have very low noise, require no power supplies, and have a wide dynamic range; Active filters are much more adjustable and versatile, can cover very wide frequency ranges, have very high input and very low output impedances, and can be configured for simple switching from low-pass to high-pass and combination for band-pass or band-reject behavior