CMOS Ring Oscillators Based on Doping-Modified Nanowire FETs: a Novel Design Strategy

We present a new Step Doped Drain and Source Nanowire FET (NWFET) using doping profile engineering to modify the energy band diagram. This transistor exhibits improved electrical characteristics suitable for digital design applications, such as the decreased off-current and subthreshold swing and the increased on-off current ratio. We also present the design of a CMOS inverter based on the proposed SDDS-NWFET. The voltage transfer characteristic (VTC) of the inverter exhibits higher noise margins compared to the inverter using traditional NWFET. All the delay parameters of the SDDS-NWFET-based inverter have higher values, which can be varied by changing the step doping concentration, N-SD. Consequently, this inverter provides flexibility in the design of ring oscillators for a wide range of oscillation frequencies. We present simulation results to demonstrate the variation of the propagation delay of SDDS-NWFET-based CMOS inverter and the oscillation frequency of CMOS ring oscillator by changing N-SD. Mathematical functions for the average propagation delay and f(osc) versus N-SD are proposed. The instantaneous current and power as well as the average DC supply power are calculated to demonstrate the dependency of the power consumption of the proposed Nanowire device-based oscillator on the varying N-SD.