Top 20 Systems Design Interview Questions for Hardware and Infrastructure Roles at FAANG
The 20 most common systems design interview questions for hardware engineers and systems engineers at Google, Meta, Amazon, Apple, and Nvidia — with answer frameworks and what interviewers are actually evaluating.
Systems design interviews for hardware and infrastructure roles are structurally different from the software systems design rounds that dominate interview-prep content online. They test your ability to reason about physical constraints — power, heat, latency, reliability, and signal integrity — alongside the higher-level architecture decisions. This guide covers the 20 questions that appear most frequently across Google, Meta, Amazon, Apple, and Nvidia hardware and systems engineering loops, along with what interviewers are actually evaluating in each.
For the RTL and chip-level technical depth that often comes up in the same loops, see our RTL design guide and VLSI physical design guide.
Power and energy systems
1. Design a power delivery network for a multi-rail server board.
What interviewers evaluate: Do you understand bulk vs high-frequency decoupling? Can you estimate PDN impedance and explain how it relates to transient response? Can you sequence rails safely?
Framework: Start with the load requirements (peak current, slew rate), work backward to the regulator topology (linear vs switching, synchronous buck for efficiency), size the input and output capacitance, and describe the power sequencing order with rationale for each step.
2. How would you design a battery management system for a wearable device?
What interviewers evaluate: Lithium chemistry constraints (voltage window, charge current limits, temperature de-rating), fuel gauging (coulomb counting vs voltage-based), and protection circuits (overcharge, overdischarge, short circuit).
Key insight to demonstrate: The safety and reliability constraints in a wearable BMS are driven as much by regulatory requirements (IEC 62368, UL certification) as by engineering choices.
3. A server's PSU fails under load. How does the system recover without losing state?
What interviewers evaluate: N+1 redundancy architecture, fast failover timing (is it fast enough to prevent memory loss?), and how hold-up time is specified for the bulk capacitance.
Signal integrity and interconnect
4. How do you design a PCB trace for a 10 Gbps serial link?
What interviewers evaluate: Controlled impedance (typically 100Ω differential), layer stackup, via stubs (and how to minimize them with back-drilling), and the role of pre-emphasis and equalization at the transmitter and receiver.
Common mistake to avoid: Treating signal integrity as purely a routing problem. The answer should include component selection (connector, package, SerDes) and the measurement plan (eye diagram at the receiver, bathtub curve analysis).
5. Explain how DDR5 differs from DDR4 from a signal integrity standpoint. What does that change in your PCB design?
What interviewers evaluate: Higher data rates (DDR5 starts at 4800 MT/s vs DDR4's 3200 MT/s), on-die ECC, higher operating voltage but lower I/O voltage, and the shift to on-DIMM power management (PMIC on the DIMM itself). The PCB impact: tighter timing budgets, stricter trace matching, and new PMIC bypass requirements.
6. You are seeing intermittent data corruption on a PCIe link in production. Walk through your debug process.
What interviewers evaluate: Structured root-cause analysis. A good answer covers: reading the PCIe error logs (AER — Advanced Error Reporting), checking link training status (Gen4 vs Gen3 negotiation), scoping the differential pair for impedance discontinuities, and measuring bit error rate with a pattern generator if needed.
Thermal and mechanical design
7. How do you calculate the thermal budget for a 25W SoC in a fanless enclosure?
What interviewers evaluate: Thermal resistance chain from junction to ambient (θJC, θCS, θSA), steady-state vs transient behavior, and the limits imposed by skin temperature requirements (typically 40–45°C for consumer devices). Can you identify where the bottleneck is and propose design changes?
8. A chip is throttling due to thermal limits in the field. How do you diagnose and fix it without a redesign?
What interviewers evaluate: First, distinguishing between a design margin problem and a manufacturing variation problem. Diagnostics: on-chip temperature sensors (PTAT circuits), thermal imaging, and correlating throttle events with workload patterns. Fixes without redesign: thermal interface material upgrade, heatsink attachment force check, and firmware-based power capping as a last resort.
Reliability and fault tolerance
9. How do you calculate the MTBF of a system from component-level data?
What interviewers evaluate: The MIL-HDBK-217 or Telcordia framework, series vs parallel reliability models, and the key assumption that matters most: the exponential failure distribution (constant hazard rate) and when it breaks down.
The important nuance: MTBF calculations from component datasheets are predictions, not measurements. Field return data is always more accurate. Interviewers want to see you acknowledge this.
10. Design a watchdog system for an embedded controller that must recover from software hangs without human intervention.
What interviewers evaluate: Independent hardware watchdog timer (separate from the MCU — if the MCU hangs, a software watchdog is useless), kick interval and timeout window, staged recovery (soft reset first, then hardware reset, then fallback firmware), and what happens if the recovery itself fails.
Systems architecture
11. How would you architect a data-center server for N+1 compute redundancy?
What interviewers evaluate: The difference between active-active and active-standby configurations, the latency cost of failover, and where the single points of failure remain even after adding redundancy (power inlet, top-of-rack switch, the server itself).
12. Design the memory architecture for a heterogeneous CPU/GPU system with 512 GB of DRAM.
What interviewers evaluate: NUMA topology, memory bandwidth partitioning between CPU and GPU workloads, coherency protocol (is the GPU a coherent agent or does it manage its own address space?), and the memory controller design constraints. This comes up heavily in Google TPU and Apple Silicon interviews.
13. Walk me through the hardware architecture of a rack-scale inference system for a large language model.
What interviewers evaluate: Compute density (accelerator cards per rack), interconnect topology (NVLink, InfiniBand, or custom), memory bandwidth vs compute balance (the roofline model), power and cooling constraints at rack scale, and failure modes when one accelerator drops from the network during an inference job.
Verification and test
14. How would you verify a custom ASIC before tapeout?
What interviewers evaluate: Verification closure methodology — simulation (UVM), formal property checking, emulation (Palladium/Veloce), and gate-level simulation. Coverage closure: code, functional, and toggle coverage. The answer should include the sign-off criteria and who owns the decision to tape out.
15. What is the difference between ATPG and functional test, and when do you use each?
What interviewers evaluate: ATPG (Automatic Test Pattern Generation) targets manufacturing defects using fault models (stuck-at, transition); functional test validates correct operation of the design. Both are needed — ATPG catches physical defects, functional test catches design bugs that survive manufacturing. For a custom ASIC, you need both at production test.
Embedded and real-time systems
16. Design an interrupt-driven data acquisition system that must sample a sensor at exactly 1 kHz with less than 1 µs jitter.
What interviewers evaluate: Timer configuration (hardware timer interrupt, not a polling loop), ISR latency and how to measure it, critical section management to protect shared buffers, and whether the MCU's real-time OS (or bare-metal interrupt priority scheme) can actually guarantee the timing.
17. How do you ensure firmware correctness during a live over-the-air update on an embedded device?
What interviewers evaluate: Dual-bank flash architecture (A/B image scheme), integrity verification before boot (hash check, signature verification), rollback capability if the new image fails to boot, and the failure mode if power is lost mid-update.
Communication and interface protocols
18. Compare I2C, SPI, and UART. When do you choose each for an embedded peripheral?
What interviewers evaluate: Physical layer differences (open-drain multi-master for I2C vs push-pull single-master for SPI), speed, pin count, and the use cases where each shines. The real question is trade-off judgment — I2C for slow shared-bus peripherals, SPI for high-speed single peripherals, UART for simple asynchronous links to a host.
19. How does USB4 achieve 40 Gbps on a single cable?
What interviewers evaluate: Thunderbolt 4 electrical substrate, 20 Gbps per lane × 2 lanes with Gen3×2 operation, USB Power Delivery (20V/5A), the alternating-mode protocol (DisplayPort, PCIe), and the role of active cable electronics in longer-length cables.
Design trade-offs
20. Your team is debating whether to build a custom ASIC or use an FPGA for a new product. What is your decision framework?
What interviewers evaluate: This is a judgment question, not a knowledge question. A complete answer covers: volume (ASICs break even only above tens of thousands of units), schedule (FPGA is faster to market), power (ASICs win significantly), flexibility (FPGAs can be updated post-deployment), and NRE cost. The best answers name a real crossover threshold and defend it with a rough calculation.
For a deep dive on this trade-off, see our FPGA vs ASIC engineer interview guide.
How to practice these
Reading the questions and frameworks above helps, but the actual skill being tested is your ability to reason through these problems live, under time pressure, while explaining your thinking clearly. The common failure mode is candidates who know the answers but cannot articulate the trade-offs fluently without notes.
On MockVise you can book a mock systems design interview with engineers who work on hardware infrastructure at FAANG companies, work through a realistic design problem from requirements to architecture, and get a written debrief on where your reasoning was sharp and where it had gaps.
Twenty questions. Work through one per day for three weeks, out loud, with a real interviewer — and you'll walk into the loop ready.
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