A. 5-GHz high-linear SiGe HBT up-converter with on-chip output balun

This paper presents a high-linearity monolithic up-converter for 5-GHz wireless LAN applications. The circuit, implemented in a 40-GHz-f/sub T/ SiGe HBT technology, includes a variable-gain amplifier (VGA) and a double balanced mixer. By using an integrated balun at the RF output, the up-converter guarantees an output 1-dB compression point (OCP1) of 4 dBm, while drawing a quiescent current as low as 34 mA from a 3-V power supply. A power gain of 11 dB is also achieved. Moreover, a digital control is included, providing a linear-in-dB gain characteristic with a 45-dB power gain range.