| 摘要 |
PROBLEM TO BE SOLVED: To provide a voltage current conversion circuit which constitutes an active filter which is operated with a low voltage and is superior in S/N as compared to a conventional one. SOLUTION: A first differential amplifier including transistors Q14 and Q16 for differential input, constant current sources 111 and 112, and a resistor R6, load transistors Q13 and Q15, a second differential amplifier including transistors Q17 and Q18 receiving differential inputs common to the first differential amplifier, constant current sources 113 and 114, and a resistor R7, transistors Q19 and Q20 (emitters are short-circuited to each other) to whose bases the collector outputs of the first differential amplifier are inputted respectively, and constant current sources 115, 116, and 117 are provided, and the collector current of the TR Q19 is not only reflected on controlled inputs (bases of transistors Q16 and Q18) out of differential inputs of first and second differential amplifiers but also added to the collector output current of the transistor Q18 of the second differential amplifier and is led out as a current conversion signal.
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