| 摘要 |
PURPOSE:To easily set a hysteresis loop with simple constitution by selecting properly values of a resistance connected in parallel to a PMOS transistor (TR) and a resistance connected in parallel to an NMOSTR. CONSTITUTION:When an input signal falls from a high level to a low level, the potential at a point M varies from a low level to a high level with a transfer characteristics Mu which is lower than the transfer characteristic Md at the point M in the low-to-high level transition of the input by a value depending upon the voltage drop across a resistance R1. Then when the input falls to a level low enough to invert the output of an inverter composed of trailing P2 and N2 to a low level after the potential at the point M is received, a PMOSTRP12 turns on to short-circuit the R1 again, and an NMOSTRN12 turns on to make R2 effective instead. At this time, the potential at the point M draws what is called a hysteresis loop with different routes as shown by the transfer characteristic Md at the time of low-to-high level variation of the input signal and the transfer characteristics Mu at the point M at the time of high-to-low level variation of the input signal. Further, values of R1 and R2 are adjusted to easily specify the width of hysteresis. |
