Microarchitect / RTL Design - Memory Subsystem

Job description

## **About Architect** Architect is a frontier AI lab for chip design. We build AI models and tools for on-demand custom ASICs at scale. Our goal is to co-design custom ASICs alongside evolving ML workloads, and enable a new era of domain-specific chips that unlock capabilities impossible with current hardware paradigms. Born out of Stanford Research, our team blends AI with Silicon with a founding team from Anthropic, Google DeepMind, Meta SuperIntelligence, xAI, Apple and Intel. ## **What You’ll Do** As a Founding Member of the Technical Staff on the RTL Design team at Architect, you’ll own the AI-driven microarchitecture and RTL design of the memory subsystem going into production silicon. You will define, drive, and revise the block-level micro-architecture specification for memory controllers, memory hierarchy management, and memory-side accelerators — ensuring maximum bandwidth utilization, minimal latency, and efficient power delivery for compute-intensive ML workloads. ### **Core Responsibilities** - **Own the memory subsystem RTL end-to-end**: from DDR/HBM controller design through code generation, lint, CDC, synthesis, and timing closure using our AI-driven design flow. - **Design and implement memory controllers**: including DDR5/LPDDR5X PHY-side controller logic, HBM3/HBM3E pseudo-channel controllers, command scheduling (open-page/close-page policies, bank-level parallelism), refresh management, and ECC/RAS engines. - **Architect the memory hierarchy**: including multi-level cache controllers, scratchpad memory managers, coherency protocol engines (where applicable), prefetch engines, and bandwidth partitioning/QoS mechanisms to serve diverse traffic profiles from ML accelerator datapaths. - **Design memory-side accelerators**: near-memory compute logic, scatter-gather DMA engines, address translation/remapping units, compression/decompression engines co-located with memory interfaces, and intelligent prefetchers tuned for ML access patterns. - **Work directly with the principal architect** to refine microarchitectural specs, resolve implementation trade-offs (bandwidth vs. latency vs. area vs. power), and feed area/timing/power realities back into the architecture and internal AI systems. - **Define and maintain interface specifications**: DDR PHY interfaces (DFI), HBM PHY interfaces, on-chip SRAM interfaces, AXI/ACE/CHI for memory-facing fabric ports, and custom interfaces for near-memory accelerator datapaths. - **Build and maintain RTL infrastructure** for our in-house AI-driven flow: design automation scripts, regression flows, lint/CDC waivers, and integration collateral for the memory subsystem. - **Close collaboration with DV**: Support verification bring-up with memory timing models, protocol-compliant BFMs, SVA assertions for JEDEC protocol compliance, coverage plans targeting worst-case scheduling scenarios, and architectural documentation for verification closure. - **Close collaboration with SW and ML**: Support and guide our SW and ML experts to revise and improve our in-house AI flow based on your memory subsystem domain expertise — particularly around workload-driven memory access pattern optimization. - **Support FPGA prototyping** on Xilinx for early functional validation of memory controllers, including bring-up with DDR MIG IPs and HBM validation platforms. ## **What We’d Like to See** ### **Required Qualifications** - **Degree**: Bachelor’s, Master’s, or PhD in Electrical Engineering, Computer Engineering, or a closely related field. - **Experience**: 5+ years (10+ preferred) in RTL design with at least one advanced-node tapeout experience involving memory subsystems (DDR/LPDDR/HBM controllers, cache hierarchies, or memory-intensive SoC subsystems). - **Memory Interface Expertise**: Deep familiarity with JEDEC memory standards — DDR5/LPDDR5X command/address protocols, timing parameters, training sequences, and/or HBM2E/HBM3 pseudo-channel architecture, stack addressing, and interleaving schemes. - **Memory Controller Design**: Hands-on experience designing or owning memory controller blocks including command schedulers, bank state machines, refresh engines (per-bank, fine-granularity), read/write turnaround optimization, and PHY interface timing (DFI or proprietary). - **Memory Hierarchy Architecture**: Experience with multi-level cache design (tag/data arrays, replacement policies, coherence protocols), scratchpad controllers, or unified memory architectures with partitioning and QoS. - **SystemVerilog**: Clear, synthesizable, lint-clean RTL with strong design habits — parameterization for multi-standard support (DDR5/HBM3), modularity for channel/pseudo-channel instantiation, and configurability for different capacity/bandwidth targets. - **Block-Level Depth**: Hands-on experience with SRAM controllers and arbiters, bank conflict resolution, address hashing/interleaving, ECC encode/decode engines, and high-bandwidth data movement between on-chip and off-chip memory. - **SoC Methodology**: Solid grasp of synthesis, timing constraints, clock domain crossings (PHY-to-controller domain, multi-frequency memory interfaces), reset strategies, AMBA protocols (AXI, ACE, CHI), and power management for memory subsystems. - **Python**: Strong skills for design automation, performance modeling, regression infrastructure, and tooling. - **PPA Ownership**: Experience taking a memory controller or cache subsystem from RTL through synthesis and working with PD teams on timing/area/power closure — particularly for high-frequency controller logic and wide data buses. ### **Bonus Qualifications** - Experience with HBM integration: interposer-level considerations, PHY calibration, thermal management impacts on refresh. - Familiarity with CXL memory pooling, Type 3 device controllers, or disaggregated memory architectures. - Near-memory or processing-in-memory (PIM) design experience. - Low-power design techniques: DVFS-aware memory scheduling, partial-array self-refresh, clock gating of idle channels, power gating of unused banks. - FPGA prototyping experience (Xilinx Vivado/Vitis) with DDR MIG or HBM subsystem IP integration. - SVA assertions for JEDEC protocol compliance (command sequencing, timing parameter checking, training state machines). - Prior IP building and delivery experience for DDR/LPDDR controllers, HBM controllers, or cache subsystem IPs. - Performance modeling: experience building or using cycle-accurate memory system simulators (e.g., DRAMSim, Ramulator) to validate microarchitectural decisions. - Domain-specific research contributions: publications or patents in memory systems, memory scheduling algorithms, or memory-centric compute architectures for ML workloads. ## **Why Architect** You’ll join a founding team building the future of chip design at the intersection of AI and silicon. Your memory subsystem expertise will directly shape production ASICs — enabling the bandwidth and efficiency that ML workloads demand — and influence how AI transforms hardware development from spec to tapeout.