| 摘要 |
PURPOSE:To obtain a BPF having a pass band of 60-72MHz on a dielectric board by decreasing an inductance of a coil through the impedance conversion, converting the circuit into a circuit having lots of capacitors and using the plane circuit. CONSTITUTION:The impedance conversion is attained by providing a tap B' to a coil L1, and the circuit including capacitors and an ideal transformer required for the conversion is converted B into a pi circuit comprising capacitors Ca-Cc by means of the Norton conversion. Then, this conversion B is attained by the plane circuit. That is, the coil is made spiral so as to have an inductance and the capacitor is formed by a plane electrode and a distributed capacitance of coil pattern. Coils 11, 13 are formed by the pattern of L1 and coils 10, 12 have a pattern of L4. Then, the capacitor Cb is formed by the distributed capacitance of plane electrodes 26a, 26b. A capacitor C4 is formed between patterns 28a and 28b. A capacitor C1 is formed equivalently between patterns 27a and 27b, between patterns 31a and 31b, or the like. The short amount of coils is formed by patterns 8, 9 on the board 6. |
