| 摘要 |
PURPOSE:To attain the increase in accuracy of an A/D converter by offsetting a prescribed signal to an analog input section of an A/D converter to average a digital signal after A/D conversion. CONSTITUTION:An offset signal of m/n-level (0<=m<n) of the LSB level of an A/D converter circuit 10 is added to an analog input signal from an offset generating circuit 11 and the added signal is applied with A/D conversion by the circuit 10. An output digital signal (b) of the circuit 10 is averaged by an averaging circuit 12 to output a signal (c). In this case, the timing of the circuits 11, 10 and 12 is controlled to add the m/n-level of the LSB by the timing generating circuit 13 once or over at a half period 1/2f0 of the frequency f0 required by the digital signal. When the timing (t) is an odd number, the input signal is subjected directly to A/D conversion (10) and when the (t) is an even number, the offset signal is added and subjected to A/D-conversion (10). With n=2 and m=1, the coding with accuracy as twice as coding using the single A/D converter 10 is attained. |
