Top 10 Common RTL coding style mistakes that increases power and area in digital designs

 1. Unoptimized Clock Gating
   - Mistake: Using enable signals directly on flip-flops instead of proper clock gating.
   - Impact: Increases dynamic power due to unnecessary clock toggling.
   - Fix: Use integrated clock gating (ICG) cells provided by the library.


2. Redundant or Glitchy Logic
   - Mistake: Poorly structured combinational logic leading to glitches.
   - Impact: Glitches cause unnecessary transitions → higher dynamic power.
   - Fix: Balance logic paths, use pipelining, and minimize cascaded combinational logic.


3. Non-Pipelined Long Combinational Paths
   - Mistake: Long chains of combinational logic without pipelining.
   - Impact: Increases critical path delay, requiring higher drive strength cells → more area & power.
   - Fix: Insert pipeline registers to break long paths.


4. Inefficient State Encoding
   - Mistake: Using binary encoding instead of Gray/One-Hot for FSMs.
   - Impact: Binary encoding causes multiple bit toggles → higher switching power.
   - Fix: Use Gray code for reduced switching or One-Hot for simpler decoding.


5. Unnecessary Use of Reset
   - Mistake: Using synchronous resets on all flip-flops when not needed.
   - Impact: Extra reset logic increases area and power.
   - Fix: Use reset only where necessary (e.g., control registers, not data paths).


6. Overuse of High Fan-Out Signals
   - Mistake: Driving a signal to many destinations without buffering.
   - Impact: Requires large buffers → more area and power.
   - Fix: Insert buffer trees or use register duplication.


7. Inefficient Memory Access
   - Mistake: Reading/Writing memories more frequently than needed.
   - Impact: Increases memory power (dominant in SoCs).
   - Fix: Use memory banking, access gating, and burst-mode operations.


8. Wider Datapaths Than Required
   - Mistake: Using 32-bit buses when 8-bit is sufficient.
   - Impact: Wastes area and increases switching power.
   - Fix: Right-size all variables and buses.


9. Lack of Power-Aware RTL Constructs
   - Mistake: Not using `always @(*)` properly, leading to unintended latches.
   - Impact: Latches increase area and power.
   - Fix: Use `always_comb` (SystemVerilog) and ensure complete assignments.


10. Redundant Sequential Logic
   - Mistake: Using flip-flops where shift registers (SRLs) or RAMs could be used.
   - Impact: More flip-flops → higher area & power.
   - Fix: Use FPGA SRLs (if applicable) or optimized memory blocks.


General Fixes:
- Use synthesis directives (`full_case`, `parallel_case`) carefully.
- Avoid `default` assignments in case statements when full coverage exists.
- Leverage power-aware synthesis tools (e.g., UPF/CPF for multi-voltage designs).


By avoiding these mistakes, RTL designers can significantly reduce dynamic power, leakage power, and area in ASIC/FPGA designs. 


Would you like detailed examples for any of these?