| 摘要 |
<P>PROBLEM TO BE SOLVED: To limit output voltage of an operational amplifier to an arbitrary voltage value in a limiter circuit included in the operational amplifier. <P>SOLUTION: In the limiter circuit, a base of a PNP transistor Q6 is connected to transistors Q8, Q9 which are connected in series, and a voltage equivalent to an upper limit value Vup is applied to an emitter of the transistor Q8. When the base voltage of an output stage PNP transistor Q7 rises and becomes higher than voltage which is subtracted drop voltage between emitter-base of the PNP transistor from the upper limit value Vup, the transistor Q6 turns on, and base voltage of the transistor Q7 is limited so as not to rise any more. By the means, the output voltage Vout of the transistor Q7 is limited to the upper limit value Vup. <P>COPYRIGHT: (C)2008,JPO&INPIT |
