| 摘要 |
PROBLEM TO BE SOLVED: To reduce an area of a switching transistor(TR) occupied in a modulation circuit by using the switching TR with a small rated current so as to realize a large current load for an antenna coil. SOLUTION: In the modulation circuit, load switching diodes SD1, SD2 whose cathodes are connected to switching TRs ST1, ST2, that respectively have a parasitic bipolar TR, and supply a current being a prescribed multiple of a current supplied to the switching TR ST1 or ST2 to an antenna coil L1 when the diodes SD1, SD2 are conductive via the parasitic bipolar TR, are provided between the antenna coil L1 and the switching TRs ST1, ST2. |
