| 摘要 |
PURPOSE:To improve the accuracy of an A/D converter whithout changing the number of bits of the A/D converter itself, by providing reference voltage generators which generate plural different levels of reference voltage and then selecting one of these generators in response to the input signal. CONSTITUTION:A system programmer 4 switches a multiplexer 1 to fetch a desired input signal and holds it at a sample holding circuit 2 for a fixed time. This input signal is then switched to either proper one of reference voltages V1 and V2 by means of a switch device 6. Then an A/D converter 3 converts the input signal held at the circuit 2 into a digital signal (g) on the basis of the selected voltage V2. In this case, V2=V1/2 is satisfied and the accuracy of the converter 3 is improved to double compared with the case where the voltage V1 is selected. |
