| 摘要 |
PURPOSE:To obtain a threshold level with high accuracy by means of a small integrated circuit by constituting a Schmitt trigger circuit obtained by adding one stage of an output inverter to the Schmitt trigger circuit formed with an operational amplifier only. CONSTITUTION:An output of the operational amplifier 1 is received by the inverter 2 and an output of the inverter 2 is supplied to an input of the amplifier 1 via a feedback circuit RF. Since the gate potential of the inverter 2 is a potential close to a power supply voltage for both a P channel transistor (TR) and an N channel TR, the size of the TR of the inverter 2 is made smaller in comparison with the circuit system extracting a current from the output of a conventional operational amplifier. Further, output TRs Q8, Q9 of the amplifier 1 can be made small in size because of inverter drive only and the current is small. Moreover, a gate potential of the output inverter is larger, the potential drop by TRs Q10, Q11 is suppressed to a small value and the threshold level is decided by the resistance ratio of R1, R2 and Rf. |
