| 摘要 |
PROBLEM TO BE SOLVED: To provide a buffer amplifier circuit which does not increase the semiconductor area and never causes any difference between the base currents of transistors for feeding input signals and output signals to differential circuits, respectively. SOLUTION: A current fed to first current mirror circuits Q1-Q4 and level shift circuits Q18, Q19 is equalized to the base current of a fourth transistor Q25 of a current source for first, second and third transistors Q8, Q16, Q5. There is no unbalance between the current flowing in the first current mirror circuits Q1-Q4 and the current flowing in the level shift circuits Q18, Q19 due to the current amplification factor variation of the first and third transistors Q8, Q5, and there is not need of such a high resistor as in the conventional circuit, thus preventing the semiconductor area from increasing.
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