Decoder
Mano Section 4.9
Outline
• Decoder• Applications• Verilog
Example of a Decoder
Convert binary information from n input lines to 2n unique outputlines.
This particular circuit take a binary number and convert it to an octal number.
Hardware Implementation
AND and NOR Decoders
Take an n-bit address.Produce 2n outputs,One of which is activated.
(NOR Decoder)
Organization of Memory Systems
Basic SRAM and VTC
A wordline is used to select the cellBitlines are used to perform read and write operations on the cell
Cross Coupled Configuration
The cell can only flip its internal state when one of its internal cross VS.During a read op, we must not disturb its current state.During a write op, we must force the internal voltage to swing past VS to change a state.
A 2-to-4 decoder with Enable
(typo, should be a 0)
Demultiplexer
A Demux is a circuit that receives information from a singleline and directs it to one of 2n possible output lines.
Use a 2-to-4 decoder as a Demux
(typo, should be a 0)
Treat A and B as the selector bits. i.e. A and B select which bit should receive infomraiton.E is treated as the data line.
Implement a Full Adder with a Decoder
Build a Bigger Decoders
Use w to enable either top or bottom decoder.
3-to-8 decoder in verilog
3-to-8 decode
Input bits
Use a Test Bench to Generate output
Initial statements execute oncestarting from time 0.
$monitor: display variable whenever a value changes.$time display the simulation time
Run functional Simulation
Results
