Subthreshold performance of deep-submicrometer dual gate material p-MOSFET and CMOS circuits for ultra low power analog/mixed-signal applications

Analog circuits based on subthreshold operation of CMOS devices are very attractive for ultra-low power, high gain and moderate frequency applications. The effect of dual material gate (DMG) on p-MOSFET for subthreshold analog operation is systematically investigated in this paper. As p- MOSFET plays a major role in CMOS circuits as active load, we simulated and studied the analog subthreshold performance parameters like output resistance (R_o), Early voltage (V_A) and intrinsic gain of 100 nm DMG p-MOS devices. The features like transconductance enhancement and suppression of short-channel effects in DMG p- MOSFET were compared with that in the single material gate (SMG) p-MOSFET. We also studied the circuit performance of a CMOS amplifier and observed the improvement in gain for DMG p-MOS based circuit. The DMG CMOS devices are found to have significantly better performance as compared to their SMG counterpart. A more than 70% improvement in the voltage gain is observed for the CMOS amplifiers when dual-material gates, instead of single-material gates, are used in both the n- and p- channel devices.