摘要 |
A filter includes a circuit board, a low-pass filter circuit, and a high-pass filter circuit. The circuit board includes at least one metal layer, and a dielectric layer attached on the at least one metal layer. The low-pass filter circuit is defined in the metal layer, and includes a main line that has two parallel portions, and a modulating circuit serving as a capacitor connected to the main line of the low-pass filter circuit. The high-pass filter circuit defined in the metal layer includes a main line that has two parallel portions and is connected to the low-pass filter circuit, and a modulating circuit serving as a conductor connected to the main line of the high-pass filter circuit.
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