| 摘要 |
PROBLEM TO BE SOLVED: To prevent a leakage current from flowing to an analog power supply from a digital signal circuit when no analog circuit is in use in an analog switch circuit having two or more power supplies. SOLUTION: A P-channel transistor(TR) P4 and an N-channel TR N4 are connected in parallel between analog input/output terminals. The back gate of the TR P4 is connected to a back gate voltage control circuit 31. This back gate voltage control circuit 31 fixes the back gate level of the TR P4 to an analog power supply level when the analog circuit is in use and fixes the back gate level to an open level or a digital power supply level when not in use. A level at a digital signal terminal node 27 controlled by the use of the analog circuit is used to select the back gate level of the TR P4. Thus, even when a digital circuit side (node 24) outputs a high level, no leakage current flows from the node 24 to the analog power supply terminal.
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