Patent ID: 7286019

Claim:
A frequency converter comprising: a CMOS passive mixer having a mixer input node; an input amplifier operable to receive a radio frequency signal at an amplifier input node, amplify the radio frequency signal, and provide the amplified signal to the mixer input node of the CMOS passive mixer, the input amplifier comprising: a bias circuit comprising: a reference voltage generation circuit operable to receive a supplied voltage and generate a first reference voltage, the reference voltage generation circuit comprising first and second resistors connected in series between the supply voltage and the second reference voltage; an operational amplifier operable to receive the first reference voltage and produce as an output a voltage indicative of a difference between the reference voltage and a gain stage output; and a scaled common gate amplifier comprising a first transistor having a gate connected to the output of the operational amplifier and a drain connected to a first resistor; and a common gate amplifier comprising a second transistor having a gate connected to the output of the operational amplifier of the bias circuit, a drain connected to a second resistor and to the input node of the CMOS passive mixer, and a source connected to the amplifier input node; and wherein a ratio of the resistance of the first resistor to the second resistor is approximately the same as a ratio of the size of the second transistor to the size of the first transistor.