A single-piece charge-based model for the output conductance of MOS transistors

Abstract

This paper presents a physically based model of the MOSFET output conductance. The drain current and the output conductance of the MOS transistor are accurately described by single-piece functions of the inversion charge densities at source and drain. Carrier velocity saturation, channel length modulation (CLM) and drain induced barrier lowering (DIBL) are included in a single-piece analytical model. The results herein can be readily applied for first order analog circuit hand calculation.

X ray and blue print: tools for MOSFET analog circuit design addressing short-channel effects

“…The Early voltage depends on if, VDS, L and T [9]. The inversion level and drain-to-source voltage have practical physical limits that naturally establish a space of extraction: if between 1 and 1000, which means from weak to strong inversion, and VDS between 0V and the maximum voltage supply.…”

“…The temperature is kept fixed. Once the points of VA are extracted they can be stored and used for several designs because if is independent of geometry [4], and VA is not a function of the channel width W [9].…”

Novel design methodology for short-channel MOSFET analog circuits

“…Equation (5) shows the relationship between the gate voltage V G and V P . The drain-to-source saturation voltage VDSsat, equation (6), comes from (4) for a small i r .…”

“…Carrier velocity saturation, the channel length modulation (CLM), drain induced barrier lowering (DIBL), and substrate current induced body effect (SCBE) are responsible for the behavior of the drain current [6]. All those effects are normally embedded in eff and L eff .…”

“…On the other hand, VA is usually considered a constant value, see Figure 2(a) and equation (10). This is an erroneous approach because VA also has the same effects of eff and L eff [6], and therefore, also dependent on bias and geometry, as Figure 2(b) shows. Equation (12), coming from (10) and (11), relates eff and L eff to VA in a very simple expression.…”