Celestial AISoftware Engineer

Updated Apr 6, 2026

Celestial AI Software Engineer interview questions & guide 2026

Every question Celestial AI interviewers actually ask, the frameworks that win the room, and the language hiring managers respond to.

Question bank

What is a Software Engineer at Celestial AI?

At Celestial AI, the role of a Software Engineer is inextricably linked to the physical reality of our hardware. We are not a traditional SaaS company; we are architecting the Photonic Fabric™, a technology that fundamentally breaks the "Memory Wall" in accelerated computing. As a Software Engineer here, you are likely working in domains such as Verification (UVM), CAD/EDA Automation, or SoC Integration. You are building the critical software infrastructure that validates, designs, and enables our optical interconnect technology to function at the tens of terabits per second required by next-generation AI.

Your work directly impacts how hyperscalers and data centers manage the massive bandwidth and latency demands of Generative AI. Whether you are developing Python scripts to automate complex analog/mixed-signal (AMS) design flows, writing SystemVerilog to verify our optical chiplets, or architecting the firmware that manages data traffic across our Optical Multi-chip Interconnect Bridges (OMIB), your code ensures that our hardware is manufacturable, reliable, and performant. You are the bridge between theoretical physics and mass-production silicon.

Common Interview Questions

The following questions are representative of the technical depth expected in our interviews. They are designed to test your practical knowledge of the tools and methodologies used in modern semiconductor design.

Verification & UVM

"Explain the UVM phasing mechanism. How do you synchronize sequences with the DUT reset?"
"How would you model a scoreboard for a protocol that supports out-of-order transactions?"
"What is the difference between new() and create() in UVM, and why does it matter?"

"How do you approach functional coverage definition to ensure you aren't over-covering or under-covering?"
"Write a SystemVerilog constraint to generate a random address that is 64-bit aligned and within a specific memory range."

Scripting & Automation (Python/Tcl)

"Given a directory of thousands of log files, write a script to identify which tests failed and categorize the error types."
"How would you use Python to interact with a Cadence Virtuoso database to extract netlist information?"
"Describe how you would implement a check to ensure that all design files in a release match the version control tag."
"How do you handle exception handling in Tcl when automating a critical synthesis flow?"

Domain & System Knowledge

"How does a Network-on-Chip (NoC) interconnect differ from a standard bus architecture?"
"What are the specific verification challenges associated with 2.5D packaging compared to monolithic SoCs?"
"Explain the concept of 'Clock Domain Crossing' (CDC) and how you verify it."
"In a high-speed SerDes design, what are the critical parameters you need to track during simulation?"

Based on the technical demands of our open roles, you must be prepared to demonstrate expertise in the following areas.

Verification Methodologies (UVM & SystemVerilog)

For verification-focused software roles, this is the core evaluation area. You must demonstrate mastery of Universal Verification Methodology (UVM). We do not just look for test execution; we look for the ability to architect robust testbenches from scratch.

Be ready to go over:

Testbench Architecture – Building UVM environments, agents, drivers, monitors, and scoreboards.
Constrained Random Verification – Writing effective constraints to hit corner cases in complex SoCs.
Coverage Closure – Strategies for achieving 100% functional and code coverage.
Advanced concepts – Register abstraction layer (RAL), TLM transactions, and UVM phases.

Example questions or scenarios:

"How would you architect a UVM testbench for a high-speed SerDes interface?"
"Describe a difficult bug you found using constrained random stimulus and how you debugged it."
"How do you handle reuse of verification components from block level to SoC level?"

EDA Automation & Scripting

For CAD and infrastructure roles, your ability to automate design flows is critical. We rely heavily on Python, Tcl, and SKILL to glue together various tools in the ASIC flow.

Be ready to go over:

Flow Automation – Automating tasks in tools like Cadence Virtuoso, Innovus, or PrimeTime.
API Interaction – Interfacing with EDA tool APIs to extract data or drive simulations.
Infrastructure Management – Managing compute resources (e.g., SLURM clusters) and license servers (FlexLM).
Version Control – Managing design data with Git or IC Manage (gdpxl).

Example questions or scenarios:

"Write a Python script to parse a large log file from a synthesis run and extract timing violations."
"How would you automate the regression testing flow for a mixed-signal design?"
"Explain how you would troubleshoot a license checkout failure in a distributed compute environment."

Semiconductor Design Flow Knowledge

Even if your role is purely software, you cannot treat the hardware as a black box. You need to understand the ASIC design flow to be effective.

Be ready to go over:

RTL to GDSII – Understanding the steps: Synthesis, Floorplanning, Place & Route, CTS, and Signoff.
Timing Analysis – Concepts of Setup/Hold time, Static Timing Analysis (STA), and timing closure.
Physical Constraints – Understanding power, area, and thermal constraints in 2.5D/3D packaging.

Example questions or scenarios:

"Explain the difference between a functional ECO and a timing ECO."
"How does your code account for process variations in deep technology nodes (like 5nm)?"

Interview Guides

Celestial AI Software Engineer interview questions & guide 2026

What is a Software Engineer at Celestial AI?

Common Interview Questions

Verification & UVM

Scripting & Automation (Python/Tcl)

Domain & System Knowledge

The questions most likely to come up

See how a strong candidate would approach this

Manage Scope Changes in Software Development

Getting Ready for Your Interviews

Interview Process Overview

The interview process, end to end

Deep Dive into Evaluation Areas

Verification Methodologies (UVM & SystemVerilog)

EDA Automation & Scripting

Semiconductor Design Flow Knowledge

What they actually test for

Key Responsibilities

Role Requirements & Qualifications

Frequently Asked Questions

Note

Other General Tips

Tip

Summary & Next Steps