Patent ID: 7477883

Claim:
Method for increasing the sensitivity of a chain of amplifiers that comprises the steps of: amplifying a signal by means of a first amplifier with a gain factor A 1 =A 1,m *ΔA 1 , where A 1,m denotes a constant gain factor and ΔA 1 denotes a gain factor variation with 1≦ΔA 1,min ≦ΔA 1 ≦ΔA 1,max , further amplifying the signal by means of a second amplifier with a controllable gain factor A 2 ≦A 2,max , where variations ΔA 1 of the gain of the first amplifier are compensated by reducing the gain A 2 of the second amplifier, so that the difference between the chain gain factor A C =A 1 *A 2 and a target chain gain factor A T ≦A T,max becomes zero, characterised in that the signal at the output of the second amplifier is additionally fed into a divider that applies a fixed factor A 3 ≦1 to its input, that variations ΔA 1 of the gain factor A 1 of the first amplifier as well as the fixed factor A 3 are at least partially compensated by the gain factor A 2 of the second amplifier, so that the difference between the chain gain factor A C ′=A 1 *A 2 *A 3 and the target chain gain factor A T becomes minimum, and that the fixed factor A 3 is chosen so that there exist at least some combinations of values ΔA 1 and A T for which said difference can be forced to zero, and some combinations of values ΔA 1 and A T , for which said difference can no longer be forced to zero due to the limitation A 2 ≦A 2,max .