| 摘要 |
PURPOSE:To detect the variation of potential exactly without mask matching or the increment of heat history processes by keeping the difference between threshold voltages of two or more semiconductor non-volatile storage elements always constant and using the differential voltage as a reference voltage source. CONSTITUTION:Units M1, M2 are semiconductor non-volatile storage elements E<2>PROMs and respective threshold voltages Vth1, Vth2 are set up by writing voltages from terminals VG1, VG2. Writing, erasing and reading to/from the M1, M2 are executed by signals from writing, erasing and reading terminals W, E, R. After setting up the thresholds Vth1, Vth2, a pulse wave from a terminal 8 is converted into analog values by D/A converters 15, 16 and the analog values are applied to the gates of the M1, M2. When voltages reach the Vth1, Vth2, the M1, M2 are turned on, the gates TG1, TG2 are also turned on and the Vth1, Vth2 are inputted to a voltage follower circuit 10 respectively. Simultaneously, the D/A converters 15, 16 are stopped by the threshold voltages Vth1, Vth2. |
