| 摘要 |
PROBLEM TO BE SOLVED: To appropriately switch a normal mode and a test mode.SOLUTION: A dual rate receiving circuit includes: a squelch circuit 120 for providing a squelch state by shutting off an output of a 10 Gbps amplifier 110; a squelch circuit 140 for providing a squelch state by shutting off an output of a 1 Gbps amplifier 130; an LOS detection circuit 200 for outputting a LOS signal 210 indicating whether or not an amplitude of a received signal is smaller than or equal to a reference amplitude; and gate circuits 400, 600, 610, 620, 630, 640 for generating squelch control signals 800, 810 in accordance with the LOS signal 210 and a rate select signal 500 indicating a current rate of the received signal during a normal mode, and generating the squelch control signals 800, 810 in which at least either squelch control according to the LOS signal 210 or squelch control according to the rate select signal 500 is invalidated during a test mode. |
