High-performance components, sophisticated algorithms, and fast processing speeds are important, but noise is the key factor in determining the performance of electronic systems.

In a recent interview with e4ds news, Professor Cho Seong-jae of Shinhan University emphasized that “noise is the most easily overlooked, yet most critical element in electronic design.”

According to Professor Jo Seong-jae, noise generated in electronic circuits can be broadly divided into three types.

Power noise generated from the power source, noise entering the circuit from the external environment, and internal noise generated from the circuit itself.

Although recent advances in semiconductor technology have significantly reduced the noise of the components themselves, power and external noise still remain the responsibility of the designer.

In particular, power noise can be controlled to some extent through filtering, but noise coming from outside is not easy to deal with because its nature varies depending on the situation.

Professor Cho Seong-jae emphasized the need for educational programs that demonstrate, through experiments, how noise changes when resistance or impedance is changed, saying, “You need to see with your own eyes how much noise is introduced under what conditions to understand.”

Noise problems are also common in digital circuits.It's not my mother.

The difference between TTL IC and CMOS IC is a representative example. TTL maintains a stable state even when the input is open, but CMOS is sensitive to external noise when the input is open due to its high impedance characteristic.

This can result in unstable output and, in severe cases, unnecessary current consumption, heat generation, and component damage.

So, in CMOS circuits, pull-up or pull-down resistors must be considered even for unused pins.

The problem doesn't end here.

The choice between pull-up and pull-down is directly related to low-power design.

In battery-powered systems like mobile devices, even a difference of a few milliamps in current can affect product competitiveness.

Professor Cho Seong-jae said, “It is meaningless to select a low-power IC and then thoughtlessly configure the surrounding circuitry,” and pointed out the importance of a design philosophy that permeates the entire system.

Noise and power consumption are inherently a trade-off.

Lowering the impedance reduces noise inflow but increases current consumption, while increasing the impedance saves power but increases susceptibility to noise.

Therefore, designers must clearly determine whether the product's goal is low noise or low power, and then select component values and structures accordingly.

If you need to satisfy both, the answer lies in 'pattern design'.

Professor Cho Seong-jae said, “PCB pattern design is key to reducing noise while maintaining high impedance,” and explained that a comprehensive approach is needed that takes into account wiring length, layout, and even grounding structure.

Professor Cho concluded by saying, “Digital circuits are ultimately an extension of analog,” and emphasized that not only hardware engineers but also software engineers must understand noise and EMC/EMI issues.all.