Active high-pass filters and passive high-pass filters are classified according to different devices used. Passive high-pass filter: A filter consisting only of passive elements (R, L, and C) that takes advantage of the principle that the reactance of the capacitive and inductive elements varies with frequency. The advantages of this kind of filter are: the circuit is relatively simple, do not need DC power supply, high reliability; Disadvantages are: the signal in the passband has energy loss, the load effect is more obvious, the use of inductance element is easy to cause electromagnetic induction, when the inductance L is large, the volume and weight of the filter are relatively large, in the low frequency domain is not applicable. Active high-pass filter: consists of a passive element (typically R and C) and an active element (e.g., an integrated operational amplifier). The advantage of this type of filter is: passband signals within no energy loss not only, but also can enlarge, load effect is not obvious, multistage associative mutual influence is very small, when using a simple method is easy to cascade high-order filters, and filter of small volume, light weight, do not need magnetic shielding (due to not use inductive components); Disadvantages are: the passband range is limited by the bandwidth of active devices (such as integrated operational amplifier), the need for DC power supply, the reliability is not as high as the passive filter, in high voltage, high frequency, high power occasions is not applicable.
