| 摘要 |
PURPOSE:To perform A/D conversion even in a small signal area with sufficient accuracy by increasing an amplification degree when the level of the output signal of a sensor is small and decreasing the amplification degree when the level is large, and inputting the output signal to an A/D converter. CONSTITUTION:When the output voltage of the sensor 1 is <=0.05V, the outputs of comparators 12 and 13 are both at H and the amplification degree of an amplifier 17 is, for example, 100 times. The output voltage of sensor 1 is ampli fied by 100 times,A/D-converted by an A/D converter 18, and read by a micro computer 19. When the output voltage of the sensor 1 is >=0.05V and <=0.5V, the output of the comparator 12 is at L and the output of the comparator 13 is at H; and the circuit voltage of the sensor 1 is amplified by an amplifier 17 by, for example, 10 times and A/D-converted by the A/D converter 18. Fur ther, when the output voltage of the sensor 1 is >=0.5V, the outputs of the comparators 12 and 13 are both at L and the output of the sensor 1 is amplified and A/D-converted as it is. |
