Classification of Digital ICs
The classification is based on the complexity of the circuit:
- Bipolar ICs
- Unipolar ICs
Bipolar ICs
The main elements of a bipolar IC are diodes and transistors. In this classification, they are further divided into two types based on the BJT (Bipolar junction transistor) operating mode.
- Saturated Mode: In saturated logic, the transistors are driven to saturation mode, the saturated bipolar ICs are: Resistor-Transistor Logic (RTL), Diode Transistor Logic (DTL), Direct Coupled Transistor Logic (DCTL), High Threshold Logic (HTL), Transistor -Transistor Logic (TTL), Integrated Injection Logic(I2L).
- Non-saturated Mode: The non-saturated bipolar ICs are: Schottky TTL, Emitter Coupled Logic (ECL)
Unipolar ICs
MOS devices are unipolar devices and only MOSFETs are employed in these MOS logic circuits. The MOS logic families are PMOS, NMOS, and CMOS.
Characteristics of Digital ICs
Digital circuits are constructed by using different logic gates, so when we use different ICs, we have to produce different logic gates using different technologies. For the fabrication of ICs, we use semiconductor devices-bipolar and unipolar. Based on the devices, digital ICs are made which are then commercially available. When we use a bipolar device, like a transistor in the IC fabrication technology, it is known as bipolar technology. In unipolar technology, we make use of unipolar devices. e.g., MOSFETs. A group of compatible ICs with the same logic level and supply voltages for performing various logic functions which have been fabricated using specified configuration, is referred to as a logic family.
Table of Content
- Integrated Circuits
- Classification
- Characteristics
- Features
- Advantages
- Disadvantages
- Applications
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