| 摘要 |
PROBLEM TO BE SOLVED: To measure the frequency characteristics of a receiving circuit and a transmitting circuit in an on-chip manner. SOLUTION: A frequency characteristic measuring circuit includes: a first diode element 31 which has a differential input node and a differential output node, which is thermally connected with a resistor element 16 of a receiving circuit 10 comprising a differential amplifier in which the resistor element 16 is connected between the differential output nodes, and which is operated by a first constant current source 33; a referencing second diode element 32 operated by a second constant current source 34; a differential amplifier 35 for detecting a difference between the forward voltages of the first and second diode elements; and an ADC 36 for converting a potential difference amplified by the differential amplifier 35 into a digital signal Q and outputting the signal. COPYRIGHT: (C)2009,JPO&INPIT
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