Category Archive for: Bias Design in Discrete and Integrated Circuits

Epitaxial and Buried Layers

In the fabrication of most monolithic integrated circuits. the processes we have described for producing tiny P and N regions in a silicon crystal arc not applied directly to the wafer but rather to a thin crystal layer grown on the surface of the wafer. The original (wafer) crystal is called the substrate for the…

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A diffused P layer

has a sheet resistance of 125 H/square. If the P material has a conductivity of 200{) Spurn, find thickness of the layer in microns. Solution. From equation 2-6, p = 1/2000 = 5 X \0′: U· m. From equation 6-37. 5 X \0-4.E.. = 4 X 10-6 m = 4 p,m R.\ 125 • Integrated…

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Capacitors

We have mentioned that a reverse-biased diode has capacitance. Recall that capacitance exists when two conducting regions are separated by an insulator, or dielectric. In the case of a reverse-biased PN junction, there is capacitance between the P and N sides because each side is conductive and the depletion region between them acts as a…

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Packaging

Although some integrated circuits are available in cylindrical metal cases, such as the TO-5 enclosures used to package discrete transistors, the majority of modern l Cs are packaged in the case type called a dual ill-line package (DIP). These rectangular cases have rigid metal tabs. called pins. that protrude from along each side of the…

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INTEGRATED CIRCUIT BIAS TECHNIQUES

As already mentioned, it is not practical to bias integrated-circuit BJT amplifiers using resistor-capacitor’ networks, as is the practice in discrete circuits. In the'[first place, the coupling and bypass capacitors in those designs are far too large to be constructed in a monolithic . For that reason, most IC amplifiers arc amplifiers, meaning both direct-coupled and…

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Current Mirrors

The objective of using a current source in biasing is to establish a constant quiescent current l., and hence a constant in another transistor used as an amplifier. This objective is accomplished using the current mirror shown in Figure 0-29. In the figure, a current source producing constant current I is shown connected to transistor 01,…

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