Electronics Engineering (ELEX) Board Practice Exam

What is an important feature of the sum-of-products form of expressions?

1. No signal should pass through more than one gate

2. No signal must pass through more than two gates, not including inverters

3. Signal can pass through any number of gates

4. Signals can only use NAND gates

The correct answer is: No signal must pass through more than two gates, not including inverters

The importance of the sum-of-products form lies in its structure which facilitates the design and simplification of digital circuits using logic gates. The statement indicating that no signal must pass through more than two gates, not including inverters, reflects a key characteristic of the sum-of-products form. This form allows for a straightforward implementation of Boolean expressions by utilizing a combination of AND and OR operations to create a minimal and efficient circuit. In digital design, limiting the number of gates a signal must pass through helps in minimizing propagation delay and improving overall signal integrity. By restricting signals to two gate levels, designers can optimize performance and reduce the potential for errors that may arise from complex interconnections with multiple gates. Thus, this approach simplifies the logic, making it easier to analyze and troubleshoot. The other options suggest various constraints that are not inherent advantages of the sum-of-products form. For instance, saying that no signal should pass through more than one gate is overly restrictive and does not capture the flexibility offered by more complex circuits. Similarly, stating that signals can pass through any number of gates could lead to inefficient designs, while limiting signals only to NAND gates does not accurately represent the diverse gate options available when implementing sum-of-products expressions.