Subthreshold Current by Domenik Helms

1) Introduction Inside a MOSFET transistor, the basis of recent systems, the voltage at the gate contact controls the conductivity and thus the current from source to drain. Ideally, the channel current to gate voltage dependence is a heavy edge function (rf. Fig. 1). If the gate voltage is below the threshold voltage, the current through the channel is 0 and if it is above the threshold voltage, the channel current raises linearly with the gate voltage. If displayed on a logarithmic scale, simulation results for a real 130nm NMOS transistor obtained using SPICE3f5 including BSIM4.4.0 characterised with the Berkeley Predictive Technology Model (BPTM) card, we can see that real ideal behaviour (rf. Fig. 2). F