| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem in a power monitoring circuit for measuring the output power of a radio frequency (RF)-band power amplifier, that because the power monitoring circuit is placed at a position near the amplifier and detects the minute power of the amplifier, the power monitoring circuit is subject to interference from a main line, etc., through which large power passes, so a bulkhead is provided between the detector circuit and the amplifier in order to prevent electromagnetic interference of the two, which in turn brings about an increase in the complexity or size of a chassis structure.SOLUTION: An LPF is formed in either a direction from a detector circuit to a through-terminal or a direction from the through-terminal to the detector circuit by providing a bidirectional T-type LPF comprising at least one of a resistor and an inductor and a capacitor in a line connecting the through-terminal and the detector circuit. Because leakage of an RF signal to the outside is thereby prevented, and interference of the RF signal to the detector circuit via the line is suppressed, it is possible to configure a highly reliable power monitoring circuit of a simple chassis structure having no bulkhead provided between the detector circuit and the amplifier. |
