Power Reduction Techniques
3 likes1,085 views
The document discusses various low power design techniques including reducing dynamic power through lowering toggle counts, clock gating at different levels, and reducing voltage. It also discusses reducing leakage power through multi threshold voltage cells, power gating, and body biasing. The techniques aim to optimize placement and routing to decrease switching activity and lower cell drive strengths when possible.
Power Reduction Techniques
- 1. Low power design techniques - Dynamic power - Reduce toggle count - RTL clock gating - Chip level, Unit level, Block level clock gating - Inferred clock gating using ICGs -- increase clock gating percentage - Reduce voltage - Multiple Modes for use cases - Structural placement (reducing interconnect cap) - Accurate power estimation to target re-architecting dynamic power critical blocks - Reduce cell drive strengths - Reduce total std_cell area - VT sweep to achieve best subset of cells for timing closure and lower power - dont_use/dont_touch settings - Reduce glitches/noise - Reduce total net length - Clustered placement, reduce detours - Multiple modes (different Vdd, different Frequency) - split rails (VDD_mem, VDD_logic correspondingly) - Relax max_trans constraint - compromise between design robustness and over-sizing of cells - Disable high drive strength cells if timing is met - Disable complex cells - Enable Register Retiming - Pin-swapping to offload high switching nets - Useful clock skew to lower the drive strength of cells in data path - Proper Technology node selection for your design - Multiple Voltage Islands - Low power designware (DW) datapath components - Achieve best Clock tree quality (latency, skew) - Results in less hold buffers, design area - Accurate timing constraints - Not to optimize some false or relaxed paths by design - Better PLL for jitter margins - Third party IPs - Multibit flip-flops to reduce clock tree power - Custom placement - SAIF based placement, Low Power Placement (LPP) flow - Best Memory placement, Floorplanning - which affects placement, total net length - Software scheduling to avoid peak power use cases - SRAM selection - Sweep to change floorplan and reduce total net length - Low Power Flop (LP Flops) usage in Synthesis
- 2. - Leakage power - Multi VT, multi drive strengths - Leakage, area recovery using ECOs - Power gating (header/footer) - Body bias - overdrive technique - Control LVT usage in PD (allow only % of LVT cells) - 3-sigma versus 2-sigma corners - Reduces yield but better leakage - Characterized library at power corner (Scaling factors across corners will be pessimistic)