| 摘要 |
<p>PURPOSE:To shorten a time required for test by providing a voltage source for test in a signal processing circuit in a feed circuit. CONSTITUTION:A digital signal processor 17 is provided with a generator OSC which can transmit a rated frequency for test, and a digital signal is generated. This signal is subjected to D/A conversion and is supplied to an operational amplifier OP4, and the output of the OP4 is amplified by an OP1 and an OP2 and is supplied as in-phase AC voltages to terminals TIP and RING. These in- phase AC voltages are fed back to an OP3 through resistances 13 and 14. Detecting operations are performed in in-phase voltage detectors 12 and 13 to adjust an unbalanced attenuation quantity.</p> |
