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处读取流，此流等于流减去流过前一个倍增流。

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.

这种方法，较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方法，这可将准确和宽动态范围结合了起来。