| 摘要 |
PURPOSE:To generate a continuous membership function with simple circuit constitution by constituting a CMOS inverter with a PMOS FET and an NMOS FET whose threshold level and W/L are set to desired values. CONSTITUTION:A membership function generating circuit is formed by connecting an NMOS FET 3 which is always on and equivalent to a resistor in series with a CMOS inverter comprising the series connection of a PMOS FET 1 and an NMOS FET 2. With an input voltage VIN to a gate of the FET 1 and a gate of the FET 2, a waveform of a current flowing to both the FETs 1,2 is extracted from a point A as a VOUT. The FETs 1,2 being components of the CMOS inverter act like switches and actually, in the CMOS inverter characteristic, a region with a current flowing called the transition region exists. The transition region is fluctuated with a threshold level of each of the PMOS and NMOS and W/L (where W is a width of the gate and L is the length of the gate). When the threshold level and the W/L are designed properly, a desired membership threshold level is obtained. |
