White paper – From geometry to the watt

PREMIUM·S.A.
Technical White Paper — Power Conversion

From geometry to the watt

Huawei’s temporal scaling (the Tau Law and LogicFolding) and why high-voltage power delivery, close to the chip, becomes the new frontier of performance, efficiency and infrastructure cost.
τ
Document
PRM-WP-2026-014
Version
v1.0 · Technical draft
Scope
R&D · Energy · Data Center · e-Mobility
Classification
Internal / Partners under NDA

0 Executive summary

The constraint that shifts the frontier toward power

At ISCAS 2026 in Shanghai, Huawei proposed replacing the geometric scaling of Moore’s Law with temporal scaling: optimizing the time it takes a signal to propagate across the chip (the τ constant) rather than the size of the transistor. Its LogicFolding architecture aims to gain density and performance through 3D integration and shorter critical paths, on mature nodes that China can actually fabricate.

For Premium, what matters is not the dispute over whether τ deserves to be called a «law.» It is the inevitable physical consequence of any path that stacks more logic into less volume —be it Huawei’s, TSMC’s, Apple’s or NVIDIA’s—: power density rises, heat concentrates, and the performance ceiling stops being set by the transistor and starts being set by the ability to bring clean energy to the die and to extract the resulting heat.

When scaling is measured in time rather than in size, the bottleneck moves from the lithographer to the power engineer. High-voltage energy delivery, with conversion as close as possible to the load, goes from being infrastructure to being a lever of performance and cost.

This document traces that causal chain across four derivatives —energy consumption, performance, heat extraction and voltage architecture— and places Premium’s opportunity at the center of the last three.

1 The paradigm shift

What Huawei proposed, and what is real

On 25 May 2026, He Tingbo —president of Huawei’s semiconductor business— presented the Tau (τ) Scaling Law and two supporting technologies: LogicFolding, which folds 2D circuits into vertical 3D stacks to shorten critical-path wiring, and UnifiedBus, a protocol to reduce communication latency at the system level.

The central idea is sound and not new in itself: below ~10 nm, interconnect delay (the wiring’s RC constant) dominates over gate delay. The whole industry is already moving toward system scaling —backside power delivery on the wafer, 3D stacking, hybrid bonding, the CFET roadmap—. What Huawei does is turn that axis into corporate doctrine, because sanctions (no ASML EUV lithography since 2023) close the geometric axis for it.

Figures announced for LogicFolding (first Kirin, Q4 2026)
+53.5%
transistor density versus a conventional SoC (up to 238 M/mm²)
+40%
energy efficiency in the main cores
+12.7%
maximum clock frequency (up to 3.1 GHz)
1.4nm
equivalent density it aspires to reach in 2031

Critical reading

«Density equivalent to 1.4 nm» is not being at 1.4 nm. It is functional density through stacking, and stacking shifts the problem —it does not eliminate it— toward three fronts that are precisely the domain of power and thermal electronics:

  • Volumetric power density: more active logic in fewer mm³.
  • Current delivery: feeding the inner layers of a 3D stack without the distribution network (PDN) «choking» them.
  • Dissipation: extracting heat from inside a solid, not just from a surface.

In other words: Huawei’s path, like those of its rivals, increases the strategic value of advanced power conversion and cooling. The rest of the document develops why.

2 Derivative I — Energy consumption

Two layers of energy: the one that computes and the one lost along the way

A computing system’s consumption splits into two layers with very different dynamics:

Compute layer (on the die)

Dynamic energy roughly follows P ≈ α·C·V²·f. Reducing τ and wiring length lowers the effective capacitance C and allows, for the same frequency, operating at a lower voltage V —and the dependence on V is quadratic—. This is where the +40% efficiency that LogicFolding claims lives. It is a real gain, but bounded to the chip.

Distribution and cooling layer (off the die)

At rack and data-center scale, a growing fraction of the energy never reaches computation: it is lost in voltage conversions, in distribution (I²R losses) and in moving heat (cooling overhead, reflected in the PUE). As AI accelerators scale from hundreds of watts to several kilowatts per package, this second layer dominates total cost of ownership.

The efficiency the circuit designer gains inside the die can be lost —multiplied— in the power and cooling chain if the voltage architecture does not evolve at the same pace. That is Premium’s space.

3 Derivative II — Performance

The performance ceiling is, increasingly, a power ceiling

Temporal scaling explicitly recognizes that modern performance —and very particularly that of AI— is limited by data movement, not by transistor count. UnifiedBus and LogicFolding attack that «memory wall.» But there is a second wall, physical and less discussed:

  • A chip can only switch as fast as it can be fed. Increasingly aggressive current peaks (di/dt) demand a very-low-impedance PDN and point-of-load (PoL) regulators millimeters from the silicon.
  • A chip can only sustain its frequency while it can be cooled. Thermal throttling is the most direct way a cooling failure turns into a performance loss.

Thus, the +12.7% in frequency that LogicFolding promises only materializes in the field if power delivery and thermals keep up. Delivered performance is the minimum between what the silicon can do and what the power infrastructure allows it to do.

4 Derivative III — Heat extraction

From a surface problem to a volume problem

3D stacking changes the nature of the thermal problem. In a flat chip, power is dissipated per unit of surface (W/cm²); in a 3D stack it concentrates per unit of volume (W/cm³), and the inner layers sit far from any exchange surface. The progression of solutions is well known:

Thermal stage Indicative capacity Power implication
Forced air up to ~0.5–1 kW/package Enough for classic SoCs; exhausted for AI.
Direct-to-chip liquid (D2C) ~1–3 kW/package Emerging standard in AI racks.
Immersion / advanced cold plate several kW Rack density >100 kW.
Embedded microfluidics (in-stack) experimental Cooling the inner layers of the 3D.

Critical coupling: copper versus coolant

In a 3D stack, the power delivery network (copper, vias, planes) and the cooling channels compete for the same height budget (Z-height). They cannot be designed separately: every watt saved in distribution losses is one watt less to extract, and every millimeter freed by a denser power architecture is room for cooling. Power and thermals become a single co-design problem.

5 Derivative IV — Voltage architecture

Bringing high voltage close to the chip: the quadratic lever

Here is the core of Premium’s argument. Delivered power is P = V · I. For a given power, raising the voltage V proportionally reduces the current I. And since conduction loss is Ploss = I² · R, that loss falls with the square of the current reduction. It is the difference between a linear improvement and a quadratic one.

Relative conduction loss (same power, same conductor)

100%
12 V

6.25%
48 V

0.09%
400 V (HVDC)

0.02%
800 V (HVDC)
high
~0

For equal power carried by an equal conductor, going from 12 V to 48 V reduces conduction loss ~16×; moving to HVDC classes makes it practically negligible. The penalty then shifts to the conversion stages, which is where high-density power electronics competes.

The delivery chain and the sector’s direction

The design consequence is twofold: raise the distribution voltage and bring the final conversion close to the load, minimizing the high-current segment. The industry is already on this path:

Power delivery spine: voltage drops and current rises toward the die


Grid
Rack
Board
PoL
Die

HVDC ~400–800 V
48 V
12 V → core
<1 V

↑ current
↑↑
↑↑↑
hundreds of A

Goal: keep high voltage along the longest possible segment and convert to low voltage / high current only in the last millimeter.

  • Rack/row level → HVDC. The sector is migrating toward direct-current distribution in the 400–800 V class to feed AI racks of hundreds of kW to megawatts, reducing copper, losses and the number of conversions.
  • Bus level → 48 V. The de-facto standard of the modern data center (including OCP’s Open Rack 48 V busbar) versus legacy 12 V: same power, 1/4 of the current, ~1/16 of the loss.
  • Package level → PoL and vertical delivery. Final conversion from 48 V to core voltage (<1 V) integrated under or beside the die, and even backside power delivery on the wafer, so that the very high current travels minimal distances.

Wide-bandgap (GaN and SiC) is the enabler: it allows faster, denser and more efficient converters that make this near-load conversion viable. It is exactly the terrain where Premium adds value.

6 Infrastructure and cost

Why voltage is, in addition, a capex and opex decision

Raising the distribution voltage does not only save energy: it cuts infrastructure cost. The chain of effects is direct:

Lever Effect on consumption (opex) Effect on infrastructure (capex)
↑ Distribution voltage I²R loss falls with the square of the current. Thinner, cheaper conductors and busbars; less copper.
↓ Conversion stages Each avoided conversion eliminates its loss. Fewer conversion units, less space, fewer points of failure.
Conversion close to the load The high-current segment is shortened to the minimum. Simpler PDN on the board; better rack utilization.
Fewer losses → less heat Cooling overhead drops (better PUE). Less installed cooling capacity per useful kW.

The result is a virtuous circle: fewer losses mean less heat, which means less cooling, which means less energy and less infrastructure for the same useful power delivered to the silicon. In the era of temporal scaling —where silicon densifies without getting cheaper per node— system savings shift decisively to the power architecture.

7 Premium’s positioning

Where Premium fits in this scenario

Huawei’s move illustrates a truth that applies to the whole sector, not just to China: as performance densifies in volume, the advantage shifts toward whoever knows how to power and cool that volume. Premium operates precisely in that layer, and with criteria —lowest cost, open hardware/software, no vendor lock-in, performance— that fit a market looking for alternatives to lock-in, both technical and geopolitical.

Lines of opportunity

  • High-voltage to point-of-load conversion with wide-bandgap (GaN/SiC) for data center and AI: rack HVDC → 48 V → core, with the final conversion as close as possible to the die.
  • Power architectures for high-density racks aligned with OCP (48 V busbar, evolution toward HVDC), leveraging the open-hardware mandate against closed solutions.
  • Power–thermal co-design: modules where energy delivery and heat extraction are designed together, not separately —the real technical differentiator of the 3D era—.
  • System-scale vendor independence: a neutral power and thermal layer works the same under Western silicon (TSMC/Apple/NVIDIA) or under the Chinese path (Huawei/Ascend), covering the ecosystem’s bifurcation.

The useful paradox: sanctions pushed Huawei onto a path that increases the world’s dependence on good power delivery and cooling. That demand is agnostic about who makes the chip —and that is precisely the neutral, open space where Premium can compete.

8 Conclusion

The lithographer hands the baton to the power engineer

The τ Law is neither a new law of physics nor the end of Moore; it is constraint-induced innovation. But its value to Premium is independent of whether it succeeds as a standard: any path that stacks more compute into less volume —from East or West— concentrates power and heat, and shifts the performance and cost ceiling to the energy delivery and dissipation layer.

Keeping high voltage along the longest possible segment, converting close to the load with wide-bandgap technology and co-designing power and thermals as a single problem is the engineering answer to the era of temporal scaling. The verdict on Huawei will come with the Kirin teardowns this autumn; Premium’s is decided by how it capitalizes on a frontier that is moving, unequivocally, into its domain.

9 Sources
  1. Huawei, official press note: «HUAWEI Presents the Tau (τ) Scaling Law» (ISCAS 2026, Shanghai, 25 May 2026).
  2. CGTN: «From geometry to time: Decoding Huawei’s Tau (τ) Scaling Law» and note on the 1.4 nm-equivalent density target in 2031.
  3. 36Kr (analysis): balanced assessment of the τ Law and the redefinition of «mature process» as «high-performance process.»
  4. TechWire Asia: Ascend / DeepSeek V4 context and demand for domestic AI silicon.
  5. Canal TI: «Huawei seeks to rewrite the rules of processors» (8 Jun 2026) — starting article.
  6. Power engineering principles (P = V·I; I²R loss; P ≈ α·C·V²·f) and distribution-architecture trends (OCP Open Rack 48 V; the sector’s migration to 400–800 V class HVDC) — domain technical knowledge.

The LogicFolding figures (+53.5% density, +40% efficiency, +12.7% frequency, 1.4 nm-equivalent target in 2031) are Huawei statements pending independent validation. The voltage-loss illustrations are normalized calculations for explanatory purposes, not product specifications.

PREMIUM S.A. · Power conversion systems · Barcelona
Technical White Paper PRM-WP-2026-014 · v1.0 · June 2026
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