| 摘要 |
<P>PROBLEM TO BE SOLVED: To allow a mixed noise to be removed between a sample holding unit and an A/D converter. <P>SOLUTION: A noise removing circuit 4 is provided between a sample holding unit 3 and an A/D converter 5. In the noise removing circuit 4, a direct current flow rate signal 3A from the sample holding unit 3 is sent to one input terminal of an operational amplifier 43 through a buffer 41 as a first input signal S1 and is sent to another input terminal of the operational amplifier 43 through a high-pass filter 44 and a buffer 42 as a second input signal S2. The high-pass filter 44 allows a signal with a predetermined frequency or higher included in the direct current flow rate signal 3A to pass through as a noise component. The operational amplifier 43 obtains a difference between the first input signal S1 ((flow rate signal component)+(noise component)) and the second input signal S2 (noise component) and outputs the difference (flow rate signal component) as a direct current flow rate signal 4A to the A/D converter 5. <P>COPYRIGHT: (C)2012,JPO&INPIT |
