Patent ID: 7173406

Claim:
A circuit for controlling RF amplifier gain comprising: an input transistor having an input transistor control terminal operable to receive an input transistor control voltage and further having an input transistor current terminal operable to pass an input current; a first buffer transistor having a first buffer transistor control terminal operable to receive a buffer transistor control voltage and further having a first buffer transistor current terminal operable to pass a first leakage current; a first leakage block operable to pass the first leakage current and further operable to generate a first leakage voltage proportional to the first leakage current; an output transistor having a current terminal operable to pass a current having a 0 Hz output current component and a second buffer transistor having a second buffer transistor control terminal operable to receive the buffer control voltage and further having a second buffer transistor current terminal passing a second buffer transistor current operable to control the 0 Hz output current component; wherein the circuit generates the buffer transistor control voltage in proportion to the input current, and wherein the circuit generates the input transistor control voltage proportionate to the first leakage current, and wherein the circuit generates the input current by summation of a fixed component and a control current component from a controlling adjustable current source, whereby the adjustable current source controls the 0 Hz output current component and a gain of the output transistor.