Reduction of the Voltage Noise of Preamplifiers by Chopping Synchronized with DSP

The voltage noise of preamplifiers limits a sensitivity of many systems in the case of the low value of an internal resistance of a signal source. The offset and 1/f noise as a special case of this noise can be reduced by some variant of chopping technique as it is known for DC amplifiers. This idea is used for new principle of reducing of the white voltage noise. In comparison to classical chopping technique the suitable synchronous DSP enables to differentiate chopped usable signal from voltage noise with frequencies around chopping frequency.