|
| Criteria | References |
| [4] | [16] | [17] | [18] | [19] | [15] | [9] |
|
| Technique | Stacking and length sizing, power gating in standby, and compression | Buffered read, and reconfigurable UDVS support | Buffered read, control of supply, buffered voltages and SA | Single-ended, 2% bit redundancy, body, header and footer bias | Segmented virtual grounding | Column-wise write, DCVSL read control | Schmitt trigger based |
| Main novelty | Using ROM and new cell design | Reconfigurability | Redundancy in SAs | New cell design | Super-threshold read | Soft-error addressing | Using ST design |
| Technology | 0.18 μm | 65 nm | 65 nm | 0.13 μm | 0.13 μm | 90 nm | 0.13 μm |
| Size (bits) | 64 | 64 K | 256 K | 2 K | 40 K | 32 K & 49 K | 4 K |
| Frequency (KHz) | ~35 at 450 mV
121 at 500 mV | 200,000 at 1.2 V
500 at 250 mV | 25 at 350 mV | 205 at 300 mV
21.5 at 210 mV | 100,000 at 400 mV | 581.4 at 300 mV
0.5 at 160 mV | 620 at 400 mV |
| Area overhead | 910% to 6 T | Not reported | 30% to 6 T | 42% to 6 T [20] | 8% to 6 T | 61% to 8 T |
~200% to 6 T |
| Total leakage/size (pA) | Not reported | ~700 at 1.2 V
~30.5 at 250 mV | ~24 at 350 mV
~21 at 300 mV | ~122 at 300 mV | 27 at 400 mV | ~24.11 at 300 mV | ~90 at 400 mV |
| Energy/access/size (fJ) | ~0.000058 at 500 mV | 0.167 at 400 mV | ~0.396 at 350 mV | 0.488 at 340 mV
0.38 at 300 mV | 0.17 at 400 mV | 0.056 at 300 mV
(Write)
0.094 at 300 mV (Read) | 50% and 18% lower dynamic and leakage power to 6 T at 175 mV |
| Min voltage (mV) | 450 | 250 | 350 | 193 | 360 | 160 | 160 |
| transistors | 14 T | 8 T | 8 T | 6 T | 6 T | 10 T | 10 T |
| Bit error rate | Not reported | Read static noise margin (SNM) eliminated | Read SNM eliminated | 2% at 120 mV | 3.5% at 330 mV | 60.3 mV mean Read and ~91 mV mean Hold SNM at 300 mV | ~56.5 mV mean Read and ~118 mV mean Hold SNM at 400 mV [21] |
| Min energy voltage (mV) | 450 | 400 | 350 | 340 | Not reported | 160 | 160 |
| Pros | Low energy | High performance | Low read error rate | Variability aware design | Very high performance | Low energy, high read SNM | Low voltage, high read SNM |
| Cons | Large area overhead, SNM not discussed | PVT variations not discussed | Low frequency | Still high leakage current | Not DVS enabled | Leakage increase at typical temp | Large area overhead |
|
