Patent ID: 7084704

Claim:
An amplifier system, comprising: a variable gain amplifier having: a differential pair circuit having a first three terminal device and a second three terminal device; a first control terminal that receives a first control voltage derived from a differential input control voltage; degeneration resistive elements coupled between the differential pair circuit and the first control terminal; a second control terminal that receives a second control voltage derived from the differential input control voltage, the second control voltage opposite in polarity to the first control voltage; and collector load resistive elements coupled between the differential pair circuit and the second control terminal, the collector load resistive elements being substantially the same type as the degeneration resistive elements, wherein a gain of the system is determined by a physical dimension ratio of the collector load resistive elements to the degeneration resistive elements for the differential input control signal equal to zero volts; a second variable gain amplifier having: a second differential pair circuit having a first three terminal device and a second three terminal device; a third control terminal that receives a third control voltage derived from a second differential input control voltage; second degeneration resistive elements coupled between the second differential pair circuit and the third control terminal; a fourth control terminal that receives a fourth control voltage derived from the second differential input control voltage, the fourth control voltage opposite in polarity to the third control voltage; and second collector load resistive elements coupled between the second differential pair circuit and the fourth control terminal, the second collector load resistive elements being substantially the same type as the second degeneration resistive elements, wherein a gain of the second variable gain amplifier is determined by a physical dimension ratio of the second collector load resistive elements to the second degeneration resistive elements at the second differential input control voltage equal to zero volts, wherein the gain of the second variable gain amplifier is inversely proportional to the gain of the variable gain amplifier.