The picoammeter reads the current at the last dynode, which is equal to the anode current minus the current flowing to the previous dynode.

皮安计在最后一个倍增电极处读取电，此电等于阳极电减去一个倍增电极的电。

The big disadvantage is the loss of accuracy and resolution, but some digital picoammeters combine accuracy and dynamic range by combining autoranging and digital log conversion.

方法，较大的缺点是损失了准确度和分辨率。然而，也有些数字式皮安表，采用自动量程和数字对数变换的方法，可将准确和宽动态范围结合了起来。