Patent ID: 7397307

Claim:
An amplfier arrangement having an adjustable gain, comprising: a signal input (In, Inx) for supplying a signal, an amplifier output (Out, Outx) for outputting an amplified signal; a first amplifier circuit, whose input is connected to the signal input and which comprises an output node; a second amplifier circuit, which is connected to the first amplifier circuit to form a negative feedback loop; an output circuit having a signal input which is connected to the output node and having an output which forms the amplifier output (Out, Outx) of the amplifier arrangement, the output circuit being designed such that its gain can be selected between at least two gain settings, wherein at least one of: the output circuit comprises of a switchable cascode stage (K) for changing the gain, the signal input of the first amplifier circuit is coupled to the signal output of the second amplifier circuit via a complex load, and the at least one output node is connected to the signal input of the second amplifier circuit, the signal input of the second amplifier circuit is connected to the signal output of the second amplifier circuit via a charge store (C 1 , C 2 ), the first amplifier circuit comprises a supply potential terminal, which is coupled to a supply potential input of the second amplifier circuit for re-using a portion of a supply current fed to the first amplifier circuit, the first amplifier circuit is arranged between a supply input and a supply output, said supply input connected to a current source, and the second amplifier circuit comprises a supply input connected to the supply output of the first amplifier circuit, the output circuit comprises a input terminal coupled to a supply output terminal of the first amplifier circuit for re-using a portion of a supply current fed to the first amplifier circuit, and the output circuit has a primary amplifier branch having a first amplifier transistor pair (M 5 , M 6 ) and having a cascode transistor pair (M 9 , M 10 ), which is connected downstream of the first amplifier transistor pair (M 5 , M 6 ), and also has a secondary branch having a second amplifier transistor pair (M 8 , M 7 ) and the cascode stage (K).