A novel analytical model for subthreshold current of a generic double-gate MOSFET (DGMOSFET) with gate-to-source/drain underlaps is proposed. The accuracy of the new model is verified based on comparisons with previously published models and numerical simulation results. With the proposed current model, effectiveness of back gate biasing, back gate asymmetry, gate work function engineering, and gate underlap engineering techniques are evaluated for suppressing the subthreshold leakage currents. Independent gate bias with gate underlap engineering significantly reduces subthreshold leakage currents as compared to standard tied- gate DGMOSFETs. © 2011 IEEE.