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Full Custom Digital IC Design of Priority Encoder 74LS 147 & 148
Team members
Bhargav-l401 Srikanth-452
Venkatesh-459 Vishesh Thakur Singh-460
What is an “Encoder”
• An encoder is a device or a combinational circuit that converts information from one format or code to another.
• Digital Encoder are more commonly called a Binary Encoder takes all its data inputs one at a time and then converts them into a single encoded output.
• An "n-bit" binary encoder has 2n input lines and n-bit output lines
4 to 2 encoder
Priority Encoder:
•A priority encoder is a special type of encoder whose output corresponds to the currently active input which has the highest priority. So when an input with a higher priority is present, all other inputs with a lower priority will be ignored.
Types of Priority Encoders(a) IC SN54/74 LS147
(b) IC SN54/74 LS148
• 8-to-3 bit priority encoder • 10-to-4 bit priority encoder
8 to 3 priority encoder
Functional Block Diagram of 74LS148
• Output A0=∑(1,3,5,7)
• Output A1=∑(2,3,6,7)
• Output A2=∑(4,5,6,7)
10 to 4 priority encoder
10 X 4
Priority Encoder
Lowest priority
Highest priority
D0
D9
Y0
Y1
Y2
Y3
Functional Block Diagram of 74LS147
8 X 3 Priority EncoderSchematic View Symbol view
Verifying Functionality of 74LS147
Schematic view of 10 X 4 Priority encoder
Symbol of 74LS147
Functional Verification of 74LS148
Layout of 74LS148
Layout of 74LS147
Applications
Keyboard Encoder
Interrupt Requests
Positional Encoders
Priority Encoder Navigation
Targets achievedS.No: Specifications: Value(74LS148) Value(74LS147
)1. Technology 180nm 180nm
2. Supply (Vdd) 1.8v 1.8v
3. Area 62.26 um. x 283.15 um.
76.97 um. x 279.2 um
4. Power without Parasitics(w)
5.69809658e-07 -1.0852728e-05
5. Power with Parasitics(w)
2.1360425e-06 -8.6488442e-07
Future Scope
•16-to-4 Priority Encoder:-
As many as 16 interrupts can be serviced based upon their priority
Thank You