Difference Between CPLD and FPGA

CPLD and FPGA are programmable logic devices. A Complex Programmable Logic Device (CPLD) is a type of programmable logic device used to create digital circuits. FPGA is an abbreviation for Field Programmable Gate Array, which is a type of programmable logic device used to build digital circuits.

Read this article to find out more about CPLD and FPGA and how they are different from each other.

What is CPLD?

CPLD is an abbreviation for Complex Programmable Logic Device. It is a digital programmable logic device with a programmable logic array (PLA) and a programmable interconnect. CPLDs have been developed to perform a wide range of logic functions and are often used in digital circuits to handle data processing, control, and communication.

In a CPLD, the programmable interconnect connects the output of one logic cell to the input of another. The interconnect can be designed to generate a wide range of logic connections, allowing complicated logic functions to be created. The interconnect is often made up of a matrix of programmable switches that connect the logic cells' inputs and outputs.

One of the benefits of CPLDs is their ease of use. Because CPLDs typically have a specified link structure, they can be designed and implemented faster than FPGAs. (Field Programmable Gate Arrays). They are also less expensive than FPGAs, making them an attractive option for low- to medium-complexity systems.

What is FPGA?

FPGA is an abbreviation for Field Programmable Gate Array, which is a type of programmable logic device used to build digital circuits. FPGAs are constructed from a grid of programmable logic blocks that can be coupled to perform sophisticated logic tasks. FPGAs feature more logic blocks than CPLDs and are therefore better suited for implementing larger and more complicated logic functions.

For implementing simpler logic operations, CPLDs are generally faster and more power-efficient than FPGAs. FPGAs are more flexible and provide greater performance and scalability when it comes to implementing larger and more complicated logic operations. Furthermore, because of their bigger size and better level of integration, FPGAs are often more expensive than CPLDs.

The logic cell, also known as a configurable logic block, is the fundamental building block of an FPGA. A CLB is made up of a look-up table (LUT), a flip-flop, and a programmable interconnect. The LUT is a memory block that can be designed to perform a specific logic function. The flip-flop stores the logic function's output, and the programmable interconnect connects the output of one CLB to the input of another.

FPGAs often have a large number of CLBs that can be configured in a two- dimensional array or matrix. An FPGA's connection topology is far more versatile than that of a CPLD, allowing for more complicated designs. The interconnect is often made up of programmable switches that may be set to connect the CLBs' inputs and outputs.

Difference between CPLD and FPGA

The following table highlights the major differences between CPLD and FPGA −




Logic Cells

It has a small number of logic cells.

It has a large number of logic cells.

Interconnect Structure

It has a fixed interconnect structure.

It has a flexible interconnect structure.


Less Flexible

More Flexible


Low Cost

High Cost

Power Consumption

Less power consumption

Higher power consumption


Less reconfigurability

More reconfigurability


Low to medium

Medium to high

Flip-flop ratios

Less flip-flop ratio

More flip-flop ratio


Best for simple applications

Best for complex applications


In conclusion, FPGAs contain a far higher number of logic cells and a more flexible connection topology, making them better suited for larger, more complicated designs. They provide greater reconfigurability and can serve a broader range of applications. Their more complex architecture can result in longer design times, higher prices, and higher power consumption.

CPLDs feature fewer logic cells and are best suited for simpler logic functions and smaller designs. They have a simpler architecture with a set connecting structure, which can result in quicker design times and reduced costs. They also consume less electricity and are better suited for low-volume production runs.

The decision between CPLD and FPGA will be determined by the unique design needs, design complexity, and project resources.

Updated on: 03-Apr-2023


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