| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a loop back test circuit which has a band sufficient for testing a Bluetooth(R) element and is capable of setting an attenuation quantity suited to a loop back test thereof to set a great amplification gain while suppressing oscillation. <P>SOLUTION: The loop back test circuit is provided with a measuring instrument connection terminal 103 for connecting a measuring instrument which is to be used also as a signal source, a DTU connection terminal 115 for connecting an element to be tested and directional couplers (106 and 114) provided between the measuring instrument connection terminal and the DUT connection terminal for branching signals to an up path and a down path, an up path 122 is equipped with an amplifier 110 for amplifying the signal from the first directional coupler and a first isolator 112 for attenuating the signal from the second directional coupler, and a down path 126 is equipped with a second isolator 118 for attenuating the signal from the first directional coupler. <P>COPYRIGHT: (C)2004,JPO |
