RF CMOS body-effect circuits

After a theoretical and analytical study of the body effect in MOS transistors, this paper offers two useful models of this parasitic phenomenon. Thanks to these models, a design methodology, which takes advantage of the bulk terminal, allows to turn this well-known body-effect drawback into an analog advantage, giving thus an efficient alternative to overcome the design constraints of the CMOS VLSI wireless mass market. To illustrate the approach, four RF building blocks are presented. First, a 0.9V 10dB gain LNA, covering a frequency range 1.8–2.4GHz, thanks to a body-effect common mode feedback, is detailed. Secondly, a body-effect linearity controlled pre-power amplifier is presented exhibiting a 5dBm input compression point (ICP1) variation under 1.8V power supply for half the current consumption. Lastly, two mixers based on body-effect mixing are presented, which achieve a 10dB conversion gain under 1.4V for a −52dB LO-to-RF isolation. Well suited for low-power/low-voltage applications, these circuits implemented in a 0.18μm CMOS VLSI technology are dedicated to multi-standard architectures and system-on-chip implementations.