A Versatile Technology Powering the Next Generation of Electronics Design
Field Programmable Gate Arrays (FPGAs) have emerged as foundational enablers fueling exponential growth in complex digital hardware emulation. With capacities crossing into the multi-billion gate threshold, modern FPGAs epitomize the abundance offered by Moore‘s Law scaling. Their fine-grained programmable logic fabric consumes this bountiful transistor budget to deliver unrivaled emulation flexibility. This powerful combination of capacity and configurability explains the meteoric rise of FPGAs for prototyping and testing across the electronics industry.
The Advent of a Disruption
FPGAs originally began as a niche alternative to rigid application-specific integrated circuits (ASICs). Their configurable logic blocks and routing interconnects allowed chip designers to iterate on designs quickly prior to costly ASIC fabrication. Early FPGAs maxed out at a few thousand gates – impressive for flexibility but severely limiting overall system complexity.
Constant exponential advances spawned families of FPGAs integrating ever-greater quantities of reconfigurable logic, memory, DSP blocks, processors, and high-speed transceivers. Modern FPGAs sport gate counts comparable to the densest custom SoC chips thanks to leading-edge manufacturing processes. For example, the Stratix 10 GX 2800 from Intel packs over two billion logic cells and 3,000 hardened IP cores across a 58 billion transistor budget.
| FPGA Family | Max Logic Cells | Process Node | Max Gates | Release Year |
|---|---|---|---|---|
| Stratix 10 GX | 2.8 million | 14 nm | 58 billion | 2017 |
| Virtex UltraScale+ VU19P | 8.2 million | 16 nm | 35 billion | 2018 |
This massive capacity perfectly complements the fundamental flexibility afforded by FPGAs. By harnessing abundant programmable resources, engineers can emulate increasingly complex hardware encompassing multi-gigahertz interfaces, heterogeneous processing pipelines with 100s of parallel execution units, and vast storage arrays – all mapped onto the sea of logic and routing inside modern FPGAs.
The next section dives deeper into the internal architecture powering this unprecedented emulation capability.
Inside an FPGA: A Configurable Powerhouse
The core building block within an FPGA is the logic block – a small colllection of memory and logical primitives like LUTs, flip-flops, and multiplexers. Tens of thousands of such blocks distributed in a programmable sea of fabric constitute the heart of the FPGA. This fine-grained logic resource gets supplemented by more dedicated functionality like high-performance DSP slices, embedded SRAM/DRAM memory, clock management, and high-speed serial I/O.
Sophisticated CAD algorithms map digital circuit descriptions from hardware description languages (HDLs) like Verilog onto these heterogenous FPGA resources. Importantly, designers need not worry about physical placement or routing – automated place and route tools handle the complex task of programming the transistors and interconnects in the fabric. This abstracts away tedious physical details allowing engineers to instead focus on crafting innovative emulation architectures using standard HDLs.
High-level overview of a modern FPGA architecture (Image Courtesy: Intel)
Furthermore, FPGA vendors offer a mature tool ecosystem spanning simulation, synthesis, implementation and debug. Fast simulation using HDL testbenches rapidly verifies functionality early in the design cycle. Synthesis tools then infer optimal logical representations targeting the underlying FPGA fabric. Physical mapping, place and route stages follow by transforming this gate level netlist into the final FPGA bitstream configuring all the programmable switches. Additional tools also help estimate final performance metrics like timing, latency and resource utilization – invaluable feedback guiding iterative emulation improvement.
The Art of Emulation
FPGA-based hardware emulation involves modeling target systems at various degrees of abstraction using HDLs like Verilog or VHDL. The choice depends on performance needs and the desired emulation depth. For instance, emulating functionality of an ARM A72 CPU core may leverage behavioral modeling of the pipeline stages rather than RTL implementation. On the other hand, pin-accurate gate level emulation is indispensable when testing complex multiprocessor cache coherence interactions and timing-critical interfaces.
In both cases, FPGAs enable early test and validation scenarios way before availability of real silicon prototypes. Software teams get a headstart on development and validation using this form of virtual prototyping. Furthermore, the configurable substrate allows extensive design exploration via selective reprogramming. Compared to the multi-month turnaround for a new chip fabrication cycle, FPGA emulation builds offer swift in-circuit verification, microwave debugger style observability, and rapid design maturation.
Overview of a typical FPGA-based hardware emulation design flow
Growing beyond functional verification, other applications leveraging FPGA emulation include:
- Aerospace/Automotive Design: Enable complex integration testing by emulating entire vehicle E/E architectures. Drive X-in-the-loop evaluation spanning mechanical, electrical and control system disciplines.
- AI Model Inferencing: FPGA emulation serves as a precursor to optimized power-efficient ASIC implementations of neural networks by exploring various quantization, pruning and mapping techniques.
- Networking Gear: Model hardware plus entire protocol stacks early in the product lifecycle using FPGA emulators guiding performance tuning.
- Quantum Computing: Emulating qubits and their control logic for small scale quantum processing units using hybrid FPGA+HPC platforms.
Rapid innovation across these high-tech sectors owes tremendous debt to FPGA emulation for accelerating pre-silicon design validation, architectural investigation, firmware development and field deployment readiness.
Rising Above Alternatives
While software simulation is an accessible emulation technique, FPGA-based approaches provide unparalleled accuracy and performance. For example, register-transfer level simulations in SystemC or similar languages rarely achieve real-world performance targets or match bit-perfectness integral to hardware. In contrast, FPGA emulation actualizes systems communicating at multi-GHz speeds with sub-nanosecond timing fidelity matching eventual silicon. JTAG hooks grant further low-level run-time visibility difficult in software simulators.
Performance hungry domains like networking gear development already mandate FPGA emulation for realistic protocol evaluation under deployment conditions. The technique provides a balanced middle-ground prior to manufacturing custom ASICs costing millions in non-recurring engineering charges. Iterative emulation builds enable identifying bottlenecks, stress testing corner cases and gathering vital performance data ultimately enhancing the quality and reliability of shipping products.
The Road Ahead
In some ways, FPGA emulation resembles the early era of computing when ingenious developers grappled with primitive but improving tools to create fascinating applications on nascent computing machines. Today, FPGAs offer a rich yet mostly untapped platform for replicating amazingly diverse and vibrant digital systems.
Ongoing exponential growth in density and performance implies emulators will continue tracking or even exceeding their ASIC equivalents. Therefore, FPGAs certainly remain the most future-proof bet for modeling complex designs, especially those that require quick turnarounds between iterations. Already, FPGA emulators enable early 5G basestation deployment, autonomous vehicle testing across thousands of simulated miles and debugging tricky parallel hardware algorithms.
As barriers limiting emulation fidelity keep falling, FPGAs will catalyze creative new use cases at the bleeding edge of electronics innovation. In time, specialized FPGA emulator appliances replicating everything from vintage arcade machines to cutting-edge supercomputer node architectures appear poised to enter mainstream consciousness. Until the tide ebbs to mark the conclusion of Moore‘s Law, FPGA emulation promises to unleash novel digital experiences and push engineering possibilities to formerly unthinkable frontiers!
