Total Charges

The ACM model has compact expressions for total charges valid in all regions. The expressions for total charges of the ACM model are shown in the Table I.

Table I. Total Charges

Fig. 1 shows the total charges including both velocity saturation and short- channel effects simulated using the ACM model implemented in Eldo simulator.

Fig. 1 . Total charges (Q_G, Q_B, Q_D, Q_S) in terms of gate voltage for V_DS = 3V and V_FB=-1V.

Capacitances

Fig. 2 presents five capacitives coefficients using the ACM model in Eldo. The solid line is obtained through total charge derivative and the dashed represents the capacitive coefficients using the ACM expressions for capacitances (Table II).

Fig. 2. Five normalized capacitances simulated using the ACM model for V_DS=3V and V_FB=-1V. Solid line represents the capacitive coefficients calculated via total charge derivative and dashed line represents the capacitives coefficients using the ACM expressions.

Table II - Capacitive Coefficients

As is presented in Fig.3, the usual approach using in ACM model considering C_gb=C_bg is a good approximation, specially because difference occurs in the region where these capacitive coefficients are small.

Fig. 3. Numerical comparison between C_gb and C_bg.

INTRODUCTION