Intermodulation distortion of low noise silicon BJT and MOSFET fabricated in BiCMOS process

Even though BiCMOS process has an ability to make both BJT and MOSFET on single-chip, only BJT has been used for BiCMOS Si-MMIC LNA because of its low noise and high gain performance under low d. c. supply power. But the distortion performance of BJT should be improved for the receiver applications in some wireless systems. In this paper, intermodulation distortion characteristics comparison is carried out between BJT and MOSFET fabricated in the same BiCMOS process by the analysis based on the simplified transistor models with extracted device parameters. The analytical result shows that MOSFET has lower intermodulation distortion characteristics compared with BJT, and the result is evaluated by the measurements. In order to obtain both low distortion and low noise characteristics, a two-stage Si-MMIC LNA is developed by using BJT as the 1st stage and MOSFET as the 2nd stage of LNA. The fabricated LNA performs N F of 2. 45 dB, gain of 19. 3 dB, IIP3 of -14. 6dBm and OIP3 of+4. 7dBm under 3 V/7. 2mA d. c. supply power.