A low distortion bipolar mixer for low voltage direct up-conversion and high IF systems

This paper describes the implementation of a low distortion mixer for direct up-conversion and high IF systems. A Gilbert cell with a low distortion transconductance constitutes the mixer core. A current feedback loop is used to linearize the transconductance stage, achieving an alternate channel leakage of -71 dBc with a power penalty of 15%. The mixer operates from 2.7 to 7.5 V of supply voltage and over a temperature range of -40 to 85/spl deg/C. It provides -3 dBm output power while drawing 7.5 mW from a 3-V supply. The mixer is implemented in 1-/spl mu/m BiCMOS for a global system for mobile communications (GSM) chip set.