Patent ID: 7593701

Claim:
A gain control circuit comprising: a mixer sub-circuit for multiplying differential linear input currents with a complementary frequency signal for providing upconverted differential signals; a variable gain sub-circuit having gain transistors for passing the upconverted differential signals with a gain corresponding to a gain control voltage, as amplified differential signals; and a current source circuit including a voltage to current circuit for converting complementary input voltage signals into corresponding current signals having noise components; and a noise reducing circuit for receiving the corresponding current signals and filtering out substantially all the noise components, the noise reducing circuit generating the differential linear input currents, and including; current to voltage converters for converting the corresponding current signals into voltage signals; low pass filters for receiving the voltage signals and for providing noise reduced voltage signals; and, voltage to current converters for receiving the noise reduced voltage signals, and for generating the differential linear input currents in response to the noise reduced voltage signals.