| 摘要 |
<p>Disclosed is a directional coupler which has excellent characteristics even when parasitic inductance is present in the coupling line. A directional coupler (11R) is constructed by providing a resistor (Rx) between a signal input port (23) and a CPL (coupling) port (25) and also between a signal output port (24) and an ISO (isolation) port (26). By providing the resistors (Rx) in this way, a real-number-component cancelling signal can be input to the coupling line (22) through the resistors (Rx), and the output of the ISO port (26) can therefore be reduced and directionality can be improved. That is, by adjusting the resistors (Rx) to have a resistance value which cancels the real number component of parasitic inductance (Lp) present in the coupling line (22), the output (isolation) of the ISO port (26) becomes substantially zero, thereby making it possible to improve directionality. It is therefore possible to realise a directional coupler which has excellent characteristics.</p> |
