| 摘要 |
PURPOSE:To extend the input voltage range without deteriorating the accuracy of an A/D converter, by multiplying a prescribed gain Y to an input signal X, A/D-converting the X, Y, inputting the result to a computer and comparing the X, Y with the preset conversion upper and lower limits. CONSTITUTION:An analog input signal X is inputted to a multiplier (preamplifier) 2 via a hold circuit 1, and it is multiplied with an initial set gain Y from a D/A converter 4. The outputs X, Y from the multiplier 2 are A/D-converted at an A/D converter 3 and the values X, Y from the converter 3 are inputted to a computer 5. The computer 5 compares the inputted, X, Y with the preset A/D conversion upper and lower limits VH, VL. From the result of comparison, a value Z is applied to the circuit 1 and this is repeated until the values X, Y are within the range of VL<=X, Y<=VH. Thus, the A/D conversion input signal range is extended to the input voltage range of the multiplier 2 without deteriorating the accuracy of the A/D converter 3. |
