Unformatted text preview: The simpli f ed T model is shown in Fig.2. Compared to the corresponding circuit for the BJT, the MOSFET circuit replaces v tb with v tg / (1 + χ ) and r e with r s = r s / (1 + χ ) . Because the gate current is zero, set α = 1 and β = ∞ in converting any BJT formulas to corresponding MOSFET formulas. The simpli f ed T model is derived with the assumption that the body lead connects to signal ground. In the case that the body lead connects to the source lead, it follows from Fig. 1 that i sb = 0 . Connecting the body to the source is equivalent to setting χ = 0 in the MOSFET equations. Figure 2: Simpli f ed T model. 1...
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- Summer '08
- Gate, rs, Start, Assumption of Mary, VTG