PROBLEM TO BE SOLVED: To obtain a logarithmic amplifier circuit which is suitably realizes on a semiconductor circuit and with a low temperature dependence of the logarithmic characteristic of an output signal. SOLUTION: Each of amplifying and rectifying circuits S1 to Sn is constituted of a MOS differential pair 4 consisting of MOS transistors M1 and M2, and a triple tail cell 5 consisting of MOS transistors M5 to M7 and a constant current source 1. MOS transistors M3 and M4 are provided as the loads of the differential pair 4, and MOS transistors M8 and M9 are provided as the loads of the cell 5. The gates of the MOS transistors M5 and M6 form an input terminal, while the drains of M5 and M6 form an amplifying output terminal and the drain of M7 forms a rectifying output terminal.
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