Analog circuit designs are often biased to work in sub-threshold mode for low power constraints and for better gate-source voltage matching performances. Depending on process, hump effect may change MOS characteristics for negative Bulk-Source Voltage (V_BS) and have a slight impact for V_BS=0V. Actually, even without body effect, hump mainly degrades MOS matching performances in the sub-threshold area with significant temperature dependence. Thus, in order to accurately simulate bandgap performances, modeling of hump effect has to be considered.