| 摘要 |
PROBLEM TO BE SOLVED: To provide an analog signal processing circuit that properly selects its input impedance. SOLUTION: This analog signal processing circuit 10 is provided with a signal input circuit 70, a level shift section 60, an amplifier 62 and a gain amplifier 20. The signal input circuit 70 is provided with an input terminal 50, an input changeover section 52, a high impedance input path 54, a low impedance input path 56 and an output changeover section 58. The high impedance input path 54 and the low impedance input path 56 are connected in parallel. The output changeover section 58 outputs an analog signal 22, passing through either of the high impedance input path 54 and the low impedance input path 56. A low input impedance is realized, where a resistive component of the low impedance input path 56 and a resistive component in the level shift section 60 are lower than the input impedance of the high impedance input path 54. With this configuration, when the analog signal 22 passes through the low impedance input path 56, deterioration in the distortion characteristic of the transmission signal can be avoided.
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