Rather we consider how to go about establishing and maintaining a given operating point.
Our primary concern here however is not to determine what an appropriate operating point is that determination depends on a particular context of use and even more so involves a degree of judgment. In order to function properly the transistor must be biased properly, i.e., the steady-state operating voltages and currents must suit the purpose involved. It also is bounded by excessive drain current on the one hand and cutoff on the other hand. The junction field-effect transistor, for example, has a normal amplifier operating drain voltage range bounded by the VCR range for low voltages and drain-gate junction breakdown for high voltages. In general all electronic devices are nonlinear, and operating characteristics can change significantly over the range of parameters under which the device operates.
The following paragraph is a modest paraphrase of that introducing the note on BJT Biasing. Although the JFET is a different device from the BJT nevertheless various aspects of device use are similar in general concept if not in precise detail. Static terminal characteristics of two representative JFETs are examined using a PSpice computer analysis of a sophisticated device model. In this note distinctions between the J unction F ield- E ffect T ransistor (JFET) and the Bipolar Junction Transistor are examined. 1 JFET Characteristics Objective Although arguably the first transistor invented the field-effect transistor did not become established as an important semiconductor device until experience with the BJT had established a broadened understanding of semiconductor phenomena and technology.
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