ABSTRACT
Many active filters with resistors and capacitors have been replaced with a filter called a switched capacitor filter (SC filter). The switched capacitor filter allows for very sophisticated, accurate, and tunable analog circuits to be manufactured without using resistors. The main reason is that resistors are hard to build on integrated circuits because they take up a lot of space, and the circuits can be made to depend on ratios of capacitor values, which can be set accurately, and not absolute values, which vary between manufacturing runs.
