Impact of body resistance on RF linearity of SOI MOSFET circuits

Body resistances (R_B) of body-contacted (BC) partially-depleted (PD) SOI MOSFETs are adjusted by a proper layout structure. The transition in the output conductance frequency response due to the finite body resistance was eliminated. Transition-free (TF) curves for 45 nm SOI MOSFET at various biasing points were extracted. The TF concept was used to design a 2.4 GHz cascode low noise amplifier. Mixed-mode transient device and circuit simulation was performed to obtain the output signal spectrum. Simulation results of TF SOI LNA showed 6 dB and 9 dB reduction in HD3 and THD at V_in=0.1 mV, respectively, comparing with the conventional BC SOI circuit. Third order intercept point (IP3) was improved by 3 dB at V_in=0.1 mV in TF SOI LNA. Simulation results confirmed the linearity advantage of RF SOI circuit based on the transition-free operating regime.