The Top 15 Synapse Design Interview Questions To Prepare For

Getting hired at Synapse Design, a leading silicon design and engineering services company, is no easy feat. With its reputation for innovation and complex system-on-chip (SoC) designs, Synapse looks for the best and brightest hardware engineers and designers

As a candidate, you need to demonstrate strong technical knowledge, problem-solving skills, and design expertise. Preparing for the Synapse interview requires research and practice. In this article, I’ll share the 15 most common Synapse Design interview questions based on my experience interviewing with them.

Overview of the Synapse Design Interview Process

The Synapse Design interview process typically involves:

• A screening call with HR
• A written test covering digital logic, Verilog, C, and microprocessors
• 1-2 technical phone/video interviews
• An onsite interview with 4-5 rounds – technical, behavioral, design exercises

Interviews focus heavily on your understanding of digital logic RTL design verification, ASIC/SoC architectures, and software proficiency. You’ll also get algorithmic and data structure problems.

Synapse looks for people who can communicate complex technical topics clearly. They want problem solvers who can work within cross-functional teams.

Now let’s look at the top 15 most frequently asked interview questions:

1. Explain your experience with RTL-to-GDSII flow. What challenges have you faced?

This tests your understanding of the entire ASIC design flow from register transfer level (RTL) design to GDSII layouts. Highlight your hands-on experience with:

• Synthesis – converting HDL to gate-level netlists
• Floorplanning, placement, clock tree synthesis
• Routing, design rule checks (DRC), layout vs. schematic (LVS) checks
• Physical verification, silicon sign-off

Discuss challenges like timing closure, routability, signal integrity. Showcase your expertise in EDA tools and methodologies to overcome these challenges.

For example, I used advanced STA techniques for timing closure and proactive noise analysis to fix SI issues during a recent 16nm FinFET project.

2. How do you optimize power, performance, and area in ASIC/SoC designs?

The power-performance-area (PPA) tradeoff is key to digital IC design. Discuss your approach to optimizing PPA from both architecture and implementation viewpoints.

For example, I leverage architectural techniques like pipelining, parallelism, and caching to optimize performance. During implementation, I use clock gating, multi-voltage power domains, high-Vt cells, and other low-power techniques to reduce power. For area, I focus on clock tree and floorplan optimization. PPA is an iterative, cross-functional effort.

3. What is your experience with various verification techniques?

Highlight your knowledge of verification strategies like:

• Simulation – behavioral, functional, timing, power
• Formal verification
• Emulation
• FPGA prototyping

Emphasize how you’ve used techniques like coverage-driven verification, assertions, and UVM. Discuss debugging approaches and how you ensure comprehensive verification closure.

For instance, I developed a UVM testbench with constraint randomization to verify a USB 3.0 interface which helped achieve 95% functional coverage.

4. How do you perform timing analysis and closure for a complex design?

Discuss your use of static timing analysis tools and methodologies. Highlight techniques like:

• Timing budgeting, early floorplanning
• Timing-driven synthesis, optimization
• Multi-corner multi-mode (MCMM) analysis
• Jitter, SI aware STA
• Timing closure driven placement, clock tree synthesis, routing

I continuously perform STA starting from synthesizable design to GDSII layout. This helps meet timing with fewer design iterations.

5. Explain various reset schemes you have used in your designs.

Resets are crucial for initializing sequential circuits like flip-flops. Discuss different reset architectures like:

• Synchronous vs. asynchronous resets
• Global vs. local resets
• Reset removal and asynchronous to synchronous conversion

I prefer synchronous resets implemented as global reset spanning clock domains. This avoids timing closure challenges posed by asynchronous resets.

6. What experience do you have with FPGA prototyping?

FPGA prototyping validates designs before tapeout. Highlight your experience:

• Design partitioning across multiple FPGAs
• Clock domain crossing analysis
• Tool flows – RTL to bitstream conversion
• Debugging in-system with signal taps

I prototyped a video processing pipeline on Xilinx Alveo cards, which provided early software development access and helped firmware engineers integrate complex IP well before tapeout.

7. How do you design for reliability in mission-critical applications?

Reliability is paramount in automotive, medical, and other critical domains. Share techniques you use like:

• DFT/ATPG insertion for testability
• Fault injection, safety analysis e.g. FMEA
• Hardware redundancy (TMR), ECC memories
• Radiation hardening, redundancy in FPGA designs

I leverage redundancy, error correcting codes, and radiation hardening techniques when designing ICs for space applications to minimize the probability of failures.

8. What experience do you have with various interconnect protocols?

Highlight your experience with standard interfaces like:

• USB, Ethernet, PCIe, DDR
• Serial protocols – I2C, SPI, UART
• Wireless – Bluetooth, WiFi, Zigbee

Discuss your implementation of these in terms of architecture, protocol layers, and PHY design considerations.

For example, I designed a USB 2.0 device controller with considerations for packet decoding, robust clock recovery, and handling bus contention.

9. What languages and standards are you familiar with for verification?

Candidates should be well-versed in:

• Hardware description languages – Verilog, SystemVerilog, VHDL
• Verification standards – OVM, VMM, UVM
• Hardware assertion languages – SVA, PSL

I have over 5 years of experience writing testbenches in SystemVerilog UVM. I am also proficient in using SVA for assertions.

10. How do you optimize DFT implementation for a complex SoC?

Discuss your experience with design-for-testability (DFT) techniques like:

• Scan chain design – balancing length, depth, controllability
• Compression – MUX-D, EDT, X-tolerant
• ATPG, fault coverage analysis
• clock domain crossing testing

For example, I implemented cell-aware scan chain stitching and X-masking to improve tester coverage and ensure high-quality manufacturing.

11. What is your experience with CDC verification?

Explain your knowledge of clock domain crossing (CDC) analysis including:

• Synchronization techniques – 2+ flop, FIFOs, handshake
• CDC verification with STA timing exceptions
• Metastability analysis, MTBF calculation

I use a combination of STA and formal methods to verify asynchronous clock boundaries are properly synchronized and meet MTBF targets.

12. How do you verify and debug silicon bring-up issues?

Bring-up requires thorough debugging skills. Discuss your experience with:

• Lab equipment – oscilloscopes, logic analyzers, probing
• Design analysis – schematics, layout, BIST
• Microprocessor debugging – JTAG

Thorough pre-silicon verification and planning for debug access enables efficient bring-up. I leverage signal probes and on-chip monitors to gain visibility and trace the root cause.

13. What low-power design techniques are you familiar with?

Showcase your knowledge of low-power design including:

• Clock gating, multi-voltage domains
• Power gating, DVFS
• Logic optimization – gate sizing, glitch reduction
• Microarchitectural techniques – pipelining, parallelization

I apply a combination of these techniques throughout the design cycle to meet power budgets. For example, extensive clock gating helped reduce power by 20% in a recent project.

14. How do you handle large post-layout timing closure gaps?

Discuss your approach to closing timing, highlighting techniques like:

• Leveraging ECO slots
• Clock tree synthesis tuning
• Targeted buffering, gate sizing
• Soft block resizing, optimizations
• Using signoff MCMM analysis

I diagnose paths missing timing through timing reports and optimize iteratively. Collaborating with architects and designers is key to ensure architectural intent is met while closing timing.

15. Can you walk us through the architecture of a complex IP you designed?

Be ready to present a complex digital IP or SoC subsystem you architected or designed. Cover details like:

• Top-level architecture, key sub-blocks
• Interfaces and bus protocols
• Implementation details – microarchitecture, datapaths
• Verification strategy
• Challenges faced and how you overcame them

I designed a 10GBASE-R Ethernet MAC/PCS handling packet processing, buffering, and interfacing to PHY. Let