Modeling & Simulation Engineer

Positron AI specializes in developing custom hardware systems to accelerate AI inference. These inference systems offer significant performance and efficiency gains over traditional GPU-based systems, delivering advantages in both performance per dollar and performance per watt. Positron exists to create the world's best AI inference systems.

Role Overview

Build the simulation and modeling infrastructure that helps Positron AI develop inference systems before silicon is available. You will develop analytical performance models, functional and timing simulators, and virtual platforms that support architecture exploration and realistic firmware, runtime, and host software workloads. The role combines computer architecture, software engineering, and quantitative analysis: choosing the right level of detail, validating model behavior, and making simulation a reliable part of everyday engineering.

Simulation Architecture and Modeling

• Develop analytical models of inference workloads to evaluate latency, throughput, utilization, and compute, memory, and communication bottlenecks.
• Build and extend functional and timing models of accelerator compute, memory, data movement, interconnects, and control processors, with explicit tradeoffs between model fidelity and simulation speed.
• Integrate accelerator models with virtual platforms and host interface models to support realistic software workloads and connected simulation environments.
• Compare current and proposed architectures through reproducible experiments, and communicate the assumptions and limits behind each result.

Production Alignment and Engineering Infrastructure

• Keep simulator interfaces aligned with production firmware, runtime, and host software so workloads, diagnostics, and tests can carry forward to hardware.
• Validate numerical behavior and timing assumptions against reference implementations and available hardware results; build automated regression coverage that distinguishes functional correctness from performance accuracy.
• Improve simulator speed and usability through configuration tools, checkpointing, deterministic execution, tracing, observability, and test automation.

Cross-Functional Collaboration

• Collaborate closely with hardware and software architects on command semantics, scheduling assumptions, and model interfaces, keeping simulator behavior consistent with architectural specifications and execution software.
• Partner with compiler, firmware, runtime, performance, and test engineers to turn models into practical development and qualification environments.

• Strong software engineering skills in a systems language such as C++ or Rust, with experience building simulators, performance models, emulators, or comparable systems tools.
• Deep understanding of processors, memory hierarchies, interconnects, concurrency, and the effects of data movement and contention on performance.
• Experience designing and validating models with explicit goals for fidelity, determinism, and execution speed, and sound judgment about what to model or abstract.
• Strong applied mathematics and quantitative reasoning skills, with the ability to turn workload behavior into useful models and experiments.
• Ability to integrate complex software systems, debug interactions across components, and build maintainable tools that other engineers can use effectively.
• Clear technical writing and communication, including documenting assumptions, explaining discrepancies, and presenting architecture tradeoffs.

• Experience with one or more of: SystemC, Arm Fast Models (LISA), QEMU, gem5, or custom event-driven or cycle-level simulation frameworks.
• Experience modeling AI inference workloads, including tensor operations, quantization, memory traffic, and token-generation performance.
• Familiarity with embedded Linux, firmware or runtime integration, device models, PCIe, or direct memory access.
• Experience with performance traces and visualization tools such as Perfetto, model calibration, distributed simulation, or test orchestration at scale.
• Experience with functional programming in languages such as Haskell or Lean, and the ability to work with domain-specific command languages used to model and control accelerator execution.

While this role is currently posted at a specific level, we are a growth oriented organization and are open to hiring at a more senior level for the right candidate. Please note that this job description serves as a focused but generalized overview of the role; specific responsibilities and impact expectations will be tailored to the experience and seniority of the final hire.

In the first 12 months, you will help establish a representative end-to-end inference workload running through the simulation environment, with useful traces and documented fidelity and limitations. Software teams will use the models in regular development and qualification, and at least one architecture decision will be informed by a reproducible, validated simulation or modeling experiment.

• Build foundational simulation infrastructure that shapes current and future generations of inference accelerators.
• Work at the intersection of architecture, firmware, and software on hard, high impact technical problems with direct influence on real hardware decisions.

The base salary range for this role is $200,000 – $300,000.

Please note that the figures provided represent the base salary range only and do not include other elements of our total compensation package, equity, or comprehensive benefits.

At Positron AI, we value the unique expertise each candidate brings. While the range above reflects our typical expectation for the position, we reserve the flexibility to exceed this range for candidates whose specialized skills, significant experience, or unique qualifications fall outside the standard scope of the role. Final offers are determined based on a variety of factors, including internal equity, and individual impact.

We want you to do your best work and feel confident that you and your family are taken care of. That means comprehensive coverage, real time to rest, and support for your future.

Health and wellness

• Fully company paid medical, dental, and vision insurance for you and your dependents
• Company paid life and disability coverage, with voluntary options to add more
• Supplemental hospital, critical illness, and accident coverage available

Time off and flexibility

• Unlimited paid time off, we encourage everyone to truly unplug and recharge
• 13 paid company holidays
• Remote first culture with a company provided computer and home office setup

Compensation and future

• Competitive salary and equity
• 401(k) with company matching, eligible from day one

This position is open to candidates currently authorized to work in the U.S. We cannot provide new visa sponsorship for this role but are open to facilitating H-1B visa transfers for eligible candidates.

Equal Opportunity Employer. If you're excited about the role but don't meet every bullet, we'd still love to hear from you.