Electronic Circuits and Diagram-Electronics Projects and Design

MOS (Metal Oxide Semiconductor)-IC’s As already mentioned in previous blog posts, ICs based upon the active devices are of two types viz. bipolar ICs using bipolar active devices like BJT and unipolar ICs using unipolar active devices such as FET. MOS ICs based on MOSFET structure are widely used in many applications especially in the digital field. This is because of its following advantages over bipolar ICs. 1. Reduction in Size. The MOS IC typically occupies only 5% of the surface required by an expitaxial double-diffused transistor in a conventional IC. Also, a MOS resistor occupies less than 1% of the area of…

How to make an integrated transistor amplifier ? We are now in a position to illustrate how a complete tran­sistor amplifier circuit including bias resistors can be formed on a silicon wafer using the masking and photolithographic processes, described earlier. The difference now is that the masking pattern must be layed out to include the appropri­ate interconnections as well. Appearing in figures is the complete IC layout of the transistor amplifier circuit shown in figure. The five circuit elements—one capacitor, three resistors, and one transistor—and all the interconnections are produced by the same masking, etching, and diffusion process-. In an…

Types of IC Packages For the protection of ICs from external environment and to provide mechanical protection and terminals for electrical connections, various types of packages are used. Several standard packages in general use are shown in figure. The metal can type of container provides electromagnetic shielding for the IC chip which cannot be provided by plastic or ceramic packages. The plastic dual-in-line package is much cheaper than other types of packages and is widely employed for general industrial and consumer applications where high temperatures are not met with. Ceramic or metal contain­ers are used where ICs are subjected to…

The outstanding feature of an IC is that it comprises a number of circuit elements insepa¬rably associated in a single small package to perform a complete electronic circuit. We shall now see how various circuit elements (such as transistors, diodes, resistors etc.) can be fabricated in an IC form. 1.    Transistors   and   Diodes. Transistors and diodes are usually formed using the epitaxial planar diffusion process described in previous blog post. Collector, base, and emitter regions are diffused into a P-type silicon substrate, as shown in figure, and surface terminals are provided for connection. In discrete transistors the…

Production Process of Monolithic IC’s A monolithic IC is one in which all circuit components and their inter-connections are formed on a single thin wafer, called the substrate. The basic production processes for the monolithic ICs are given below : Monolithic IC Manufacturing Process 1. P-Substrate. As already mentioned in the previous article, it is the bottom most layer that serves as the body or substrate upon which the complete IC is built. A typical P-type crystal is grown in dimensions of 250 mm length and 25 mm diameter, as shown in figure. Sili­con is preferred because its characteris­tics are…

Basic Monolithic IC Circuit A simple circuit consisting of a diode, a resistor and a transistor is shown in figure. The cross-sectional view of the IC corresponding to the circuit shown in figure is depicted in other fig. The basic structure of an IC consists of the four layers of different materials. The bottom most layer, typically 200 u m thick, is a P-type silicon and serves as the body or substrate upon which the complete IC is built. The second layer, typically 25 am thick, is of N-type silicon material which is grown as a single crystal extension of the…

An integrated circuit (IC) consists of several interconnected transistors, resistors, capaci­tors etc., all contained in one small package with external connecting terminals. The circuit may be entirely self-contained, requiring only input and output connections and supply voltage to function. Alternatively, a few external components may have to be connected to make the circuit operative. On the basis of fabrication techniques used, the ICs can be divided into following three classes. Monolithic IC’s The word ‘monolithic’ is derived from the Greek monos, meaning ’single’ and lithos, meaning ‘stone’.Thus monolithic circuit is built into a single stone or single crystal i.e. in monolithic ICs,…

Merits or Advantages of Integrated Circuits The integrated circuits offer a number of advantages over those made by interconnecting discrete components. These are summarized as follows: 1. Extremely small size—thousands times smaller than discrete circuit. It is because of fabrication of various circuit elements in a single chip of semi-conductor mate¬rial. 2. Very small weight owing to miniaturized circuit. 3. Very low cost because of simultaneous production of hundreds of similar circuits on a small semiconductor wafer. Owing to mass production an IC costs as much as an individual transistor. 4. More reliable because of elimination of soldered joints and…

An Introduction to IC – Integrated Circuits The integrated circuit was introduced in 1958. It has been called the most significant technological development of twentieth century. It has radically altered the world of electronics. The profound effect of these micro-electronic ‘giants’ was first felt in the computer and digital field. First-generation electronic computers employed vacuum tubes. Vacuum tubes were replaced by transistors, cheaper in cost, smaller in size, less power consuming and reliable, in second generation computers. Third generation computers used digital ICs, largely reducing computer size and increasing computer reliability and speed. Integrated circuits have further reduced product dimensions…