HWIL FPGA Engineer

Why Castelion, Why Now

Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability.

Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability.

This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function.

As a HWIL FPGA Engineer, you will lead the FPGA architecture and development for Castelion's next-generation Hardware-in-the-Loop (HWIL) test capability. You will be a foundational member of a multidisciplinary team responsible for building a real-time test environment that enables rapid validation of hardware and algorithms before flight testing.

Working alongside simulation, hardware, electrical, mechanical, software, and guidance engineers, you'll develop FPGA-based solutions that bridge high-fidelity 6-DOF simulation with physical hardware, ultimately enabling fully closed-loop testing in representative mission environments.

This role is ideal for engineers who enjoy solving difficult real-time hardware challenges, working across multiple engineering disciplines, and building systems from the ground up.

• Lead FPGA architecture, development, integration, and verification for Castelion's Hardware-in-the-Loop (HWIL) test system.
• Develop FPGA solutions supporting real-time evaluation and closed-loop hardware testing.
• Collaborate with simulation engineers to integrate high-fidelity 6-DOF models into FPGA-based HWIL architectures.
• Design FPGA interfaces that integrate seamlessly with radar hardware, sensors, and supporting electronics.
• Develop high-performance FPGA implementations using high-level synthesis tools while optimizing generated RTL where appropriate.
• Participate in system architecture definition, interface development, and hardware design reviews.
• Develop FPGA verification strategies including simulation, timing analysis, hardware validation, and laboratory integration.
• Support bring-up, debugging, and optimization of FPGA hardware in laboratory environments.
• Partner closely with electrical, mechanical, software, and systems engineers to rapidly iterate HWIL capabilities using a crawl, walk, run development methodology.
• Contribute to the evolution of the HWIL system from early open-loop demonstrations to fully closed-loop representative mission testing.

• Bachelor's degree in Electrical Engineering, Computer Engineering, Computer Science, or a related technical discipline.
• 5+ years of professional FPGA development experience.
• Experience developing FPGA solutions using VHDL, Verilog, or System Verilog.
• Experience with Xilinx/AMD FPGA platforms and associated development tool chains.
• U.S. Citizenship required.

• Ability to generate RTL from HLS workflows while understanding and optimizing the resulting hardware implementation.
• Strong understanding of FPGA development workflows including simulation, synthesis, implementation, timing closure, and hardware debugging.
• Experience integrating FPGA designs with complex hardware interfaces and embedded systems.
• Familiarity with hardware-in-the-loop (HWIL), processor-in-the-loop (PIL), or real-time simulation environments.
• Experience supporting radar, RF, avionics, guidance, navigation, control, or aerospace systems.
• Experience working with high-speed interfaces, real-time data processing, and deterministic hardware architectures.
• Familiarity with laboratory integration, oscilloscopes, logic analyzers, and hardware debugging tools.
• Ability to collaborate effectively across multidisciplinary engineering teams in a fast-paced development environment.
• Active U.S. security clearance or the ability to obtain one is highly desired.

Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details.

Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities…