| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high gain with respect to an ac input signal while suppressing the influence of a dc offset in a differential amplifier circuit. SOLUTION: A first transistor M1 and a second transistor M2 constitute a differential pair being the input stage of this differential amplifier circuit, and both respective source terminals are connected to one end of a constant current source Ib. A third transistor M3 and a fourth transistor M4 constitute a current mirror circuit, and their drain terminals are respectively connected to the drain terminal of the first transistor and the drain terminal of the second transistor. An impedance circuit Z, wherein impedance becomes low with respect to a dc signal and impedance becomes high with respect to an ac signal, is connected between the drain terminal of the first transistor M1 and the drain terminals of the second transistor M2. COPYRIGHT: (C)2005,JPO&NCIPI
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