| 摘要 |
PROBLEM TO BE SOLVED: To provide an operational amplifier circuit having a wide input/output dynamic range. SOLUTION: A differential input stage 1 is constituted of a constant current source M2 and a differential input pair M3 and M4. An amplifying stage 2 consists of a cascode current mirror part 3 constituted of a p-channel MOS transistor, a cascode current mirror part 4 constituted of an n-channel MOS transistor, reference voltage sources M6, M8, M9 and M18, reference current sources M5, M7 and M19 and M1 and M20 which control the reference current sources. The drains of the transistor M3 and M4 are respectively connected to the drains of M14 and M15 of the amplifying stage, the drain node voltage of the input stage is made to be the minimum and an input dynamic range is extended to the maximum. The voltage between the drain and the source of each MOS transistor constituting the respective current mirror parts (3 and 4) is adopted as Vdsat being the minimum voltage value for saturation in the transistors and, then, the minimum value of the output dynamic range is made to down to 2 Vdsat.
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