FPGA vs. PLA

Attribute	FPGA	PLA
Full Form	Field-Programmable Gate Array	Programmable Logic Array
Functionality	Can implement complex logic functions	Primarily used for simpler logic functions
Flexibility	Highly flexible and reconfigurable	Less flexible compared to FPGA
Programming	Programmed using hardware description languages	Programmed using fuse links or antifuse links
Resource Utilization	Efficient utilization of resources	May have unused resources due to fixed structure

Introduction

Field Programmable Gate Arrays (FPGAs) and Programmable Logic Arrays (PLAs) are both types of programmable logic devices used in digital circuit design. While they serve similar purposes, there are key differences in their attributes that make them suitable for different applications. In this article, we will compare the attributes of FPGA and PLA to help you understand their strengths and weaknesses.

Architecture

FPGAs are based on a grid of configurable logic blocks connected through programmable interconnects. These logic blocks can be programmed to perform specific functions, allowing for a high degree of flexibility in designing complex digital circuits. On the other hand, PLAs consist of a fixed array of AND gates feeding into a programmable array of OR gates. This fixed architecture limits the flexibility of PLAs compared to FPGAs, as the logic functions are predefined.

Flexibility

One of the key advantages of FPGAs is their flexibility. Since the logic blocks in an FPGA can be programmed to perform different functions, designers have the freedom to implement a wide range of digital circuits using a single device. This flexibility makes FPGAs ideal for prototyping and rapid development of custom logic designs. In contrast, PLAs have limited flexibility due to their fixed AND-OR structure, making them more suitable for simpler logic functions that do not require frequent changes.

Performance

When it comes to performance, FPGAs generally offer higher speed and lower power consumption compared to PLAs. This is because FPGAs can be optimized for specific applications by configuring the logic blocks and interconnects to minimize propagation delays and power consumption. Additionally, FPGAs often include features such as dedicated hardware multipliers and memory blocks that can further enhance performance. On the other hand, PLAs may struggle to achieve the same level of performance due to their fixed architecture and limited optimization options.

Cost

In terms of cost, FPGAs are typically more expensive than PLAs due to their higher complexity and flexibility. FPGAs require more resources to manufacture and program, which can drive up the cost of the devices. Additionally, FPGAs often require specialized design tools and expertise to fully utilize their capabilities, adding to the overall cost of using these devices. On the other hand, PLAs are simpler in design and programming, making them a more cost-effective option for simpler logic functions that do not require the flexibility of FPGAs.

Programming

Programming FPGAs and PLAs also differs in terms of complexity and ease of use. FPGAs typically require the use of hardware description languages (HDLs) such as Verilog or VHDL to define the logic functions and interconnections within the device. While this approach offers a high level of control and customization, it can be challenging for beginners to learn and use effectively. In contrast, programming PLAs is often simpler and more intuitive, as designers can directly specify the desired logic functions using a truth table or Boolean equations without the need for complex HDLs.

Applications

Due to their flexibility and high performance, FPGAs are commonly used in a wide range of applications, including telecommunications, automotive, aerospace, and industrial automation. FPGAs are particularly well-suited for applications that require real-time processing, high-speed data transfer, and complex logic functions. On the other hand, PLAs are more commonly used in simpler applications such as address decoding, control logic, and basic arithmetic functions where flexibility and performance are not critical.

Conclusion

In conclusion, FPGAs and PLAs each have their own unique attributes that make them suitable for different types of digital circuit design. FPGAs offer greater flexibility, higher performance, and more complex programming options, making them ideal for applications that require custom logic functions and high-speed processing. On the other hand, PLAs are simpler, more cost-effective, and easier to program, making them a better choice for basic logic functions that do not require frequent changes or optimization. By understanding the strengths and weaknesses of FPGAs and PLAs, designers can choose the right programmable logic device for their specific application requirements.