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由模——数转换器提供的有效范围和测量精度,两者通常是受转换器‘宽度’或‘分辨率’——亦即,转换器提供的位数所限制。用位数表示的最大精度实质上等于分辨率。这样,一个8位转换器能够提供8位或大约±0.2%的最大精度。当然,这个最大精度仅当输入信号接近于有效范围的顶端——办即,接近于基准电压时方能获得。对于较低的输入电压,转换精度亦低。因此,转换器的有效范围受工作有效范围内要求的精度所限制。例如,研究一个单极型运用的8位 A/D 转换器,用10V 基准电压,
The effective range and measurement accuracy provided by an analog-to-digital converter, both of which are typically limited by the converter ’width’ or ’resolution’ - that is, the number of bits provided by the converter. The maximum precision expressed in terms of bits is substantially equal to the resolution. In this way, an 8-bit converter can provide 8 bits or about ± 0.2% maximum accuracy. Of course, this maximum accuracy is only obtained when the input signal is close to the top of the effective range, ie, close to the reference voltage. The conversion accuracy is also low for lower input voltages. Therefore, the effective range of the converter is limited by the required accuracy of the working range. For example, consider a unipolar 8-bit A / D converter, with a 10V reference voltage,