CPC G01N 27/128 (2013.01) [G01N 33/48721 (2013.01)] | 16 Claims |
1. A method of measuring current, comprising:
using a first charge amplifier to integrate a current to be measured;
filtering an output from the first charge amplifier using a first low pass filter module and a second low pass filter module; and
using a second charge amplifier to integrate a current derived from the filtered output from the first charge amplifier, wherein:
the first charge amplifier is reset at the start of each of a plurality of sensing frames;
at least a first sample of the output from the first charge amplifier is obtained in each sensing frame; and
the sampling of the first sample alternates from one sensing frame to the next sensing frame between sampling via the first low pass filter module and sampling via the second low pass filter module.
|