Low 1/f noise CMOS active mixers for direct conversion

The analysis of direct conversion CMOS active mixers tailored to ReFlex standard is presented. To minimize 1/f noise, the switching stage pMOS devices have large area, low biasing current. pMOS and nMOS transconductors shunted together form the input stage. A 0.35-/spl mu/m prototype performs at 900 MHz as follows: 18 dB SSB NF averaged in the 100 Hz-3 kHz band, 18 dB gain, -4-dBm IIP3, 30-dBm IIP2 with 6 mA from 2.7-V supply.