| 摘要 |
PURPOSE:To prevent the leakage of digital noises to the analog circuit through a substrate by forming the analog circuit by a MOSFET and operating the analog circuit between power supplies +V and -V and the digital circuit between the power supply +V and ground. CONSTITUTION:When the power supply -V(-5 volt) is applied to the P type semiconductor substrate 10 and the power supply +V(+5 volt) is applied to P<+> source electrodes S1, S3 with N wells, the analog circuit 11 is operated between voltage +V(+5 volt) and -V(-5 volt), and the digital circuit 12 is operated between voltage +V(+5 volt) and the GND(0 volt). Accordingly, the substrate 10 is not affected because the potential of the substrate 10 is at -V(-5 volt) and the circuit 12 uses voltage between 0 volt and voltage +V(5 volt). That is, noises do not leak to the circuit 11 through the substrate 10. In a C-MOS according to an N well system, the power supplies of the circuit 11 and the circuit 12 are isolated, and the go-round of digital noises to the circuit 11 section can be prevented. |
