Capacitor-type structures performance

In this review the basis for the chemical sensitivity of these devices will be explored and the various device structures used for these sensors will be discussed. A survey of the performance of the diode-type and capacitor-type structures will be presented and a comparison of characteristics of these two classes of solid state gas sensors will be given. 

General Behavior. For the same reasons discussed in the diode performance section, most of the work on capacitor-type C-I-S sensors has focused on structures for detecting hydrogen or hydrogen-bearing gases. Consequently, this section will mainly examine the performance of C-I-S hydrogen sensors however, detection of CO will be discussed. 

Eased on tiie system specification, a filter schematic is developed. A first sensitivity analysis (influence of component tolerances on the function) should be made to verify the manufacturability in general. Another technology-independent method uses typical parasitics, which are added to tiie schematic (e.g., capacitor with parasitic inductance or quality factor of an inductor). Eoth methods help to decide which filter type will perform best if several schematic structures are available. 

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