| 摘要 |
<p>PROBLEM TO BE SOLVED: To allow the converter to be in operation in any mode and any rate of change in the system by applying over-sampling digital conversion to an analog input signal with low accuracy and at a high conversion rate and using a low pass filter to conduct low frequency and high accuracy conversion. SOLUTION: An analog input signal X1 with pulse code modulation information is given to a delta sigma modulator 13, in which the signal is subject to over-sampling digital conversion with low accuracy and at a higher rate than a final conversion rate. In this case, a master clock frequency 15 is used to generate a high frequency conversion rate and adjustable. Then its output is filtered digitally with a low pass filter in a decimation filter 14 in which low frequency high accuracy conversion is selected from high frequency low accuracy conversion by a decimation rate 16 and an output X0 of a long word at a low rate is obtained. Succeedingly, undesired frequency components are eliminated by a digital filter with a constant impulse response. Thus, the converter is in operation in any mode and any rate of change in the system.</p> |
