| 摘要 |
PROBLEM TO BE SOLVED: To suppress variation in output voltage by holding a desired offset voltage constant by providing a reference voltage generating circuit and a current adjusting circuit and adjusting a supply current by comparing the output voltage with a reference voltage signal. SOLUTION: When an input signal IN varies from a low to a high stage, transistors(TR) N21 and N24 turn on and a driving current I2 is supplied from a TR P2 through a resistance load RL in a direction A to raise the voltage of a node NP2. When the reference voltage from a simulating circuit MC is compared and exceeded, the output of an OPAMP1 increases to raise the gate- source voltage of the P2 and the current I2 is reduced to continue the operation until the voltage becomes as high as the reference voltage. Similarly, when a low output voltage exceeds a low reference voltage, the output of the OPAMP 1 decreases and the current from a TR N1 is reduced. Consequently, even when a resistive load RL varies, it can be held at a voltage reference level by supplying sufficient current and thus the variation of the resistive load RL is compensated to hold the differential output voltage constant.
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