Chiplets: The Secret to Cheaper, Smarter Smartphone Brains (SOC).

  Chiplets: The Secret to Cheaper, Smarter Smartphone Brains (SOC).

What if your next phone’s chip cost half as much to make—and still crushed it?

SOC to chiplets

Replacing the traditional System-on-Chip (SoC) approach for smartphones, which integrates everything into a single monolithic chip typically fabricated on advanced sub-7nm processes, with a chiplet-based architecture. Let’s break this down and explore the potential benefits, challenges, and feasibility of using chiplets with high-speed interconnects to reduce costs.

The Concept

In a chiplet design, instead of putting all functions (CPU, GPU, modem, I/O, power management, etc.) on one die, you split them into separate smaller chips, or "chiplets." These chiplets could be manufactured on different process nodes tailored to their specific needs—e.g., power management and I/O on a cheaper, mature node like 16nm, while high-performance cores (CPU/GPU) stay on sub-7nm. High-speed interconnects would link them together, ideally maintaining performance close to a monolithic SoC.

Potential Cost Benefits

1. Process Node Flexibility: Advanced nodes (e.g., 5nm, 3nm) are insanely expensive due to the cost of equipment, masks, and lower yields. By moving less performance-critical components (like I/O or power management) to older, cheaper nodes like 16nm, you reduce the amount of silicon that needs cutting-edge fabrication. Mature nodes have higher yields and lower per-wafer costs.
2. Smaller Dies: Smaller chiplets are easier to manufacture with fewer defects, improving yield rates compared to a large monolithic SoC. A single defect on a big SoC can ruin the whole chip; with chiplets, you might only lose one module.
3. Modularity: Chiplets could allow companies to mix and match components for different devices (e.g., budget vs. flagship phones), reusing designs and reducing R&D costs.
4. Supply Chain Resilience: Different chiplets could be sourced from multiple foundries, reducing reliance on a single cutting-edge fab like TSMC.

Technical Feasibility

High-speed interconnects are key here, and this is where chiplet designs shine in other industries (e.g., AMD’s Ryzen CPUs). Technologies like:

• 2.5D/3D Packaging: Using silicon interposers or stacking (e.g., TSMC’s CoWoS, Intel’s EMIB) to connect chiplets with minimal latency.
• High-Bandwidth Interconnects: Standards like PCIe, CXL, or custom solutions (e.g., AMD’s Infinity Fabric) could provide the necessary bandwidth between chiplets.
• Chiplet-to-Chiplet Communication: For smartphones, you’d need interconnects fast enough to rival on-die communication in an SoC—think tens of GB/s with sub-nanosecond latency.

In theory, this could work. For example:

• CPU/GPU Chiplet: Fabbed on 5nm for performance.
• Modem/I/O Chiplet: On 16nm, where transistor density matters less.
• Power Management Chiplet: On 28nm or even 40nm, super cheap and reliable.

Challenges

1. Interconnect Overhead: Even with fast interconnects, communication between chiplets is slower and less power-efficient than on-die communication in an SoC. In smartphones, where power efficiency is critical, this could increase battery drain.
2. Thermal Management: Multiple chiplets might complicate heat dissipation in a tiny phone chassis compared to a single SoC.
3. Design Complexity: Splitting an SoC into chiplets requires redesigning the architecture and software to handle distributed computing, which could offset some cost savings with higher engineering costs.
4. Latency: I/O or modem functions might suffer if they’re not tightly integrated with the CPU/GPU, impacting real-time tasks like gaming or 5G.
5. Packaging Costs: Advanced packaging (e.g., interposers) isn’t cheap and could eat into the savings from using older nodes.

Cost Analysis

Let’s speculate with rough numbers:

• A flagship SoC (e.g., Snapdragon 8 Gen 1) might cost $50–70 to produce on 4nm, with a big chunk of that tied to the node’s complexity.
• A chiplet approach might split it into:
  • CPU/GPU on 5nm: $30–40.
  • I/O + modem on 16nm: $5–10.
  • Power on 28nm: $2–5.
  • Packaging/interconnects: $10–15.
• Total: ~$47–70. Savings depend on how much the interconnect and packaging costs offset the cheaper nodes.

If interconnects get cheaper (e.g., via mass adoption), this could indeed undercut monolithic SoC costs, especially for mid-range or budget phones where bleeding-edge performance isn’t critical.

Real-World Precedents

• AMD: Their chiplet-based Ryzen and EPYC CPUs have disrupted Intel’s monolithic dominance by offering high performance at lower cost.
• Intel: Ponte Vecchio uses chiplets for GPUs, mixing nodes for efficiency.
• Apple: While still monolithic, their M-series chips hint at modularity potential (e.g., unified memory could pair with chiplet designs).

Smartphones, though, are trickier due to size and power constraints. No major phone SoC has gone full chiplet yet, but the tech exists.

Question: What do you think, should companies like Qualcomm or MediaTek start experimenting with this?

Yes yield is a huge factor, and it’s one of the strongest arguments for chiplets in this context. Let’s dive a bit deeper into why Qualcomm or MediaTek experimenting with chiplets could make sense, especially from a yield perspective, and how that ties into cost.

Yield and Cost Connection

In semiconductor manufacturing, yield—the percentage of defect-free chips per wafer—drops as die size and process complexity increase. Modern smartphone SoCs (e.g., Qualcomm’s Snapdragon or MediaTek’s Dimensity) are big, complex chips on sub-7nm nodes. A single defect can scrap the whole SoC, and with nodes like 4nm or 3nm, defects are harder to avoid due to the tiny feature sizes and cutting-edge lithography (e.g., EUV). This drives up costs—low yields mean fewer usable chips per expensive wafer.

Chiplets flip this dynamic:

• Smaller Dies, Higher Yield: By breaking the SoC into smaller chiplets (e.g., CPU, GPU, modem, I/O), each piece has a smaller area, so a defect is less likely to ruin it. A 50mm² chiplet has a much higher yield than a 150mm² monolithic SoC.
• Mixing Nodes: Less critical chiplets (e.g., I/O, power management) on mature nodes like 16nm or 28nm have near-perfect yields because those processes are well-optimized after years of use.
• Salvageability: If one chiplet fails, you might still use the others, unlike an SoC where the whole thing’s toast.

For example, if a wafer costs $10,000 on 5nm and yields 200 good SoCs, each chip costs $50 before packaging. Split it into chiplets—say, 400 good CPU chiplets on 5nm and 800 good I/O chiplets on 16nm per wafer—the cost per functional set could drop significantly, even with interconnect overhead.

Why Qualcomm or MediaTek Should Jump In

1. Market Pressure: MediaTek’s already winning in the budget/mid-range space with cost-effective designs. Chiplets could widen that gap, letting them churn out cheaper, modular chips for diverse markets. Qualcomm, facing competition, might use chiplets to reclaim ground in mid-tier phones without sacrificing flagship profits.
2. Scalability: A chiplet approach lets them design a high-performance CPU/GPU core once, then pair it with different modem or I/O chiplets for 4G vs. 5G phones, or even region-specific needs—all without retooling the whole SoC.
3. Experimentation Window: The tech’s proven in PCs (AMD) and data centers (Intel). Smartphones are the next frontier, and early movers could lock in patents or process advantages.
4. Yield Insurance: As nodes shrink further (e.g., 2nm), yields will get even trickier. Chiplets could future-proof their supply chains.

Where They Could Start

• Mid-Range Chips: Test chiplets in something like a Snapdragon 6-series or Dimensity 7000—less risk than flagships, but big volume potential. Pair a 7nm CPU/GPU with a 16nm modem/I/O.
• Power Management: Spin off the PMIC (power management IC) as a cheap chiplet first—minimal performance hit, big cost savings.
• Partnerships: Work with TSMC or Samsung on affordable 2.5D packaging (e.g., interposers) to keep interconnect costs down.

Hurdles to Watch

• Power Trade-Off: Higher yield might not matter if interconnects guzzle battery life—phones can’t afford that hit.
• Software: Android and apps need to handle chiplet quirks seamlessly, which might mean extra optimization.
• Upfront Cost: Redesigning for chiplets isn’t cheap initially; they’d need a long-term volume play to recoup it.

The Bottom Line

If Qualcomm or MediaTek pulled this off, higher yields could slash per-chip costs by 20–30% (my rough guess, based on PC chiplet trends), especially for high-volume mid-range phones. It’s a no-brainer to at least experiment—start small, prove the concept, then scale. Imagine a $15 chip that performs like a $30 SoC today; that’s a game-changer for affordable 5G.

Write by Toor Khan and enhanced by AI chatbot.

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