Had been pretty tied up with my next engineering book lately, as well as family commitments. Well, here's the next installment:
Transistors and MOSFETs
The transistor—from its humble beginning as a discrete entity in 1947 at AT&T's Bell Laboratory, to its present highly integrated forms numbering in the millions—is the basic building block of all modern electronic devices.
Transistors can be broadly classified into two types: bipolar and unipolar (also known as field-effect transistor, or FET). The bipolar transistor has three terminals labeled base, collector and emitter, and utilizes a small base current to control or switch a much larger current between the collector and emitter. As such, the BJT can function as an amplifier in the linear range, or as a switch under saturated condition. The FET also has three terminals labeled gate, drain and source, but uses a gate voltage to control the current between the source and drain. The FET can be further divided into junction FET (JFET) and insulated or metal-oxide semiconductor FET (MOSFET).
Like the diodes, military grade transistors are similarly prefixed with JAN, JANTX, JANTXV, or simply JX before their usual 2Nxxx commercial part numbers. Likewise, SMD transistors are marked with 2 or 3 alpha-numeric codes. For example, the Fairchild MMBT2222A is the equivalent of a 2N2222A TO-18 NPN transistor. There are also transistor array ICs used mainly for driving/sinking high current loads, such as the ULN2803A.
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