Low 1/f noise and DC offset RF mixer for direct conversion receiver using parasitic vertical NPN bipolar transistor in deep n-well CMOS technology

RF characteristics of the parasitic vertical NPN bipolar junction transistor (BJT) available in 0.18 /spl mu/m foundry deep n-well CMOS technology are reported for the first time. The experimental results show that the vertical NPN BJT has about 20 of current gain, 7 V of collector-emitter breakdown voltage, 20 V of collector-base breakdown voltage, 40 V of early voltage, 2.3 GHz of cutoff frequency, and 3.5 GHz of maximum oscillation frequency at room temperature. The corner frequency of flicker noise is lower than 4 kHz at 0.5 mA. Double balanced RF mixer using V-NPN shows almost free 1/f noise as well as order of magnitude smaller DC offset with other characteristics comparable with CMOS one and 12 dB flat up to the cutoff frequency, opening the possibility of high performance direct conversion receiver implementation in CMOS technology.