RF Active Filter using active inverters with feedback circuits

摘要

The invention is used when it selectively passing or removing, as only a desired frequency component for application of the high frequency band. Already circuits for this purpose are often published previously. In particular, the basis of the filter design of the high frequency band is a filter circuit of the impedance inverter which SBCohn this invention.; On the other hand, the low-frequency uses a lot of active devices, particularly active filter using the Op Amp to such a way of reducing the size of the circuit. On the other hand, it is not easy to design the active filter because increasingly difficult to make the Op Amp to the high frequency band. Usually the active filter using an Op Amp are used, but up to several tens of ㎒, the main method of designing the above 500㎒ circuit design of the filter using passive elements so far. However, the filter has a case using only passive elements such limitations There which gradually smaller, the integration of all circuitry. In particular, the integration can be said is to design the filter using only passive elements is not possible due to the loss of the filter becomes large too. The method proposed to solve this problem is the design of the active filter.; The present invention is one of the active filter design method in this invention is required. In particular, the circuit impedance of the inverter, which serves to change the impedance value between the resonators or between the input and output terminal and the resonator at a desired level was formed by using an active element other than the passive device. Due to the use of an active impedance inverter compensate for the insertion loss generated in the passive resonator as a whole it is possible to obtain the insertion gain. The main interest in the present invention has the most active element input and output impedances are different lots, it is necessary to make equal the value, and to a method for to have an impedance desired before and after passing through the impedance inverter impedance value. In the present invention, a method was used as feedback circuits. In particular, The use of an active impedance inverter made by a number of feedback circuit can use the traditional manual filter design methods as it can be easy access to the design of the high-frequency active filter.