Gate Charge Factors

A more recent way of describing the parasitic capacitor-based effects in a mosfet is in terms of gate charge factors. In Figure 5-15, we show how these charge factors, Qgs, Qgd, and Qg,... 

Basically, we are using the gate charge factors to tell us what the effective capacitances are (and the voltage swings from 0 to Vin). We see that the effective input capacitance (Ciss), for... 

Figure 5-16 Estimating the Effective Interelectrode Capacitances from the Gate Charge Factors (Si4442DY as an example)...

The drain current Id is proportional to the charge-carrier mobility the transistor dimensions, where W and L are the channel width and length respectively, the applied voltage, where Vgs and VT are the gate-source and threshold voltage, and the insulator capacitance Cj (Eq. 1). Thus, the impact of the dielectric material on transistor performance is given by the dielectric capacitance which results from a geometrical quotient of area A and distance d (distance is the film thickness of the dielectric layer) and a material factor where s0 and er are the dielectric constant in a vacuum and of the material, respectively (Eq. 2). As consequences of these correla-... 

Several studies have examined the influence of film morphology on sensor behavior [109, 168-178]. Two main areas of interest are the influence of film thickness and grain size on the time scale for sensor response as well as the magnitude (sensitivity) of sensor response. Other factors that may influence the conductivity response are the nature of the semiconductor-metal device contacts, as well as charge accumulation at other device interfaces, such as the gate oxide in field effect sensor devices. 

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