Low-Cost Approximate Constant Coefficient Hybrid Binary-Unary Multiplier for DSP

[Ken Eguro]

Low-Cost Approximate Constant Coefficient Hybrid Binary-Unary Multiplier for DSP Applications – Link for PDF
S. Rasoul Faraji (University of Minnesota, Twin Cities), Pierre Abillama (University of Minnesota, Twin Cities), and Kia Bazargan (University of Minnesota, Twin Cities)

[CambridgeHe]

It is an interesting paper using relatively new encoding scheme for multiplier design.
Can I kindly seek you opinions –
1. It looks that CCM is a very good case study for unary representation, am I right?
2. For large coefficient cases, does HBU lead to higher error (Fig.7)? Could you please share some observation on your error comparisons versus LUT-based and shift-and-add based CCMs?
3. One interesting point is why HBU’s area drops at larger coefficient cases?

Thank you very much.

[RasoulFaraji]

1) Yes, because CCMs are single-input monotonic functions.
2) The magnitude of error can be up to 1 unit for non-optimized and 3 units for optimized ones.
3) Since HBU uses unary cores to implement a CCM, which are simple routing networks, the synthesizer simplifies the architecture as much as it can. Therefore, the number of LUT to implement HBU-based CCMs is in a range. However, the number of required LUT to implement Binary-based CCMs depends on the value of the CCM which is high for non-trivial larger CCMs.

[Dustin Richmond]

Thank you for posting your question!

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