| 摘要 |
An active poly-phase filter has a converting section and a filtering section having two first input terminals, two second input terminals and four output terminals. The converting section has first, second, fourth and fifth transistors forming a translinear circuit and a third transistor forming a current mirror circuit with the second transistor. The converting section converts unbalanced high-frequency power into a difference input between a collector current of the third transistor and a collector current of the first transistor having phase difference of &pgr; radians. The filtering section receives one collector current at the first input terminals and receives another collector current at the second input terminals and outputs a first difference output between outputs of two output terminals and a second difference output between outputs of other two output terminals such that the difference outputs has a phase difference of &pgr;/2 radians.
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