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逐次比较式8位A/D转换器的分辨率比较低只有1/256,但价格很便宜。12位的逐次比较式A/D转换器的价格要比8位的A/D芯片价格贵十几倍。虽然高位的双积分式A/D转换器的价格比较便宜,但其转换时间要比逐次比较式A/D转换器多上百倍,故在需要快速采样的场合则不能应用。本文介绍一种方法利用8位A/D芯片只增加很少元件就可以获得1/2048或更高的分辨率,其速度基本上接近8位逐次比较式A/D转换器的速度,在实际应用中效果很好。这种方法的基本设计思想是这样的:把输入范围0～5V电压分为8档,相邻两档间隔为5V/8=0.625V。若输入信号介于某两档电压之间则把输入信号与较低档的电压相减,其差必然小于0.625V,再把这个电压信号放大8倍使之变为0～5V间的信号送到8位
Successive comparison 8-bit A / D converter resolution is only 1/256 low, but the price is very cheap. 12-bit successive comparison A / D converter prices than the 8-bit A / D chip prices ten times more expensive. Although the high double integral A / D converter is cheaper, but the conversion time than the successive comparison A / D converter hundreds of times, so you need to quickly sample the occasion can not be applied. This article describes a method using the 8-bit A / D chip with only a few components can increase the resolution of 1/2048 or higher, the speed is basically close to 8-bit A / D converter compared to the speed of the actual Good effect in the application. The basic idea of this method is this: the input range 0 ~ 5V voltage is divided into 8 files, the adjacent two files interval is 5V / 8 = 0.625V. If the input signal is between a two-range voltage, the input signal is subtracted from the lower-range voltage, the difference must be less than 0.625V, then the voltage signal is amplified by 8 times so that it becomes a signal between 0 and 5V To eight