Patent ID: 7417506

Claim:
An amplifier comprising: a transistor circuit having variable amplification, the transistor circuit including a plurality of negative feedback resistors and a plurality of switches, the plurality of switches being formed such that an associated negative feedback resistor from the plurality of negative feedback resistors can be activated by operating one of the plurality of switches, the transistor circuit further comprising a single transistor stage and a plurality of negative feedback devices, the plurality of negative feedback devices comprising the plurality of negative feedback resistors, at least one switch of the plurality of switches being associated with each of the plurality of negative feedback devices so that a each of the plurality of negative feedback devices can be activated or deactivated by controlling the associated at least one switch, wherein an input of the transistor stage forms an input of the transistor circuit and an output of the transistor stage forms an output of the transistor circuit, and wherein at least one of the plurality of negative feedback devices comprises a first negative feedback resistor, a first switch, a common node, a second switch, and a second negative feedback resistor, the first and second negative feedback resistors being coupled to the common node via the first and second switches; and a controller operable to control at least one of the plurality of switches and to activate at least one of the plurality of negative feedback resistors to set a desired amplification.