Question

Which of the following statements is not correct about a CPLD (Complex Programmable Logic Device)?

(1) A CPLD is a logic device that consists of multiple SPLDs interconnected on a single chip

(2) A CPLD is based on Product-Of-Sums (POS) architecture

(3) A CPLD consists of multiple groups of PAL with programmable interconnection

(4) A CPLD can be used to implement a large logic function

1. 1
2. 2
3. 3
4. 4

Answer 1

Correct Answer - Option 2 : 2

CPLD (Complex Programmable Logic Device):

• These are devices that have relatively higher complexity than the likes of PALs but are less complex than FPGAs or Field Programmable Gate Arrays.
• A CPLD is essentially made up of numerous macrocells, each of which consists of disjunctive normal form expressions as well as other logic operations for more specific applications for logic implementation.
• They contain a combination of AND and OR gates arranged in an array that can be programmed to perform and execute many different logic functions.
   

Some of the CPLD features which are common with PALs are:

• Non-volatile configuration memory. Unlike many FPGAs, an external configuration ROM isn't required, and the CPLD can function immediately on system start-up.
• For many legacy CPLD devices, routing constraints most logic blocks to have input and output signals connected to external pins, reducing opportunities for internal state storage and deeply layered logic.
   

Other features that are common with FPGAs are:

• A large number of gates available. CPLDs typically have the equivalent of thousands to tens of thousands of logic gates, allowing the implementation of moderately complicated data processing devices. PALs typically have a few hundred gate equivalents at most, while FPGAs typically range from tens of thousands to several million.
• Some provisions for logic more flexible than sum-of-products expressions, including complicated feedback paths between macrocells, and specialized logic for implementing various commonly used functions, such as integer arithmetic.
   

Conclusion: It follows SOP architecture. So, option 2 is wrong.