What is parasitic capacitance? (April/May 2010)
In electrical circuits, parasitic capacitance is an unavoidable and usually unwanted capacitance that exists
between the parts of an electronic component or circuit simply because of their proximity to each other
No satisfactory integrated circuits exist if high Q inductors with inductance of values larger than 5 micro Henry are required they are usually supplied by a wound inductor which is connected externally to the chip. Therefore the use of inductor is normally avoided when integrated circuits are used.
Based on IC Technology
Monolithic
Hybrid
Based on Active devices
Bipolar
Unipolar
Based on isolation technique
PN junction
Dielectric
Based on types of FET
MOSFET
JFET
1 . Miniaturization and hence increased equipment density.
2. Cost reduction due to batch processing
3. Increased system reliability due to the elimination of soldered joints
4. Improve functional performance
5. Matched devices
6. Increased operating speed
In general bipolar integrated circuits use epitaxial layer process in which resistivity epitaxial is formed over low resistivity substrate to provide isolation between the epitaxial growth and the substrate the doping used in both layers is of opposite type due to this heavily doped buried layer is formed. The buried layer is also called diffusion layer.
The conductivity of the semiconductor increases when small impurity is added to it the process of adding impurity is called doping while the impurity to be added is called dopant so Ion implantation is a process of adding dopant to the Silicon substrate. The ion implantation process is controllable reproducible and also there are no unwanted side effects.
The process of introducing impurities in to the selected regions of silicon wafer is called diffusion. The rate at which various impurities diffuse into the Silicon will be of the order of 1 micro metre per hour at the temperature range of 900 degree Celsius 1100 degree Celsius. The utility and terms of the tendency to move from regions of Ion concentration to lower concentration.
