Introduction
The critical issue that occurs in the printed circuit boards is distortion. Mostly, these distortions have been found in the circuits running at a higher speed. As a result, it prevents to transfer of the data at faster rates. Thus, makes the circuit and the device unreliable and questionable. Two main kinds or types of distortions occur in any circuits. That is the linear distortion and the non-linear distortion. Harmonic distortion in PCB comes under the nonlinear distortion.
Linear and Non-Linear Distortions in PCB
There are two significant kinds of distortion. These include linear and non-linear distortion. Numerous sources produce these distortions. Therefore, affects differently on the modulated signals. For example, the one source of linear distortion is the discontinuity in the material properties. Likewise, dispersion distortion that comes under linear distortion arises because of the dispersion in the PCB substrate.
Nonlinear distortions occur in nonlinear circuits. It includes the intermediation distortion and occurs when there are two frequency components as input in any none linear circuit. Further, the major distortion that arises under this none linear circuit is the “Harmonic Distortions“.
What is Harmonic Distortion?
Harmonic distortions are the variations that occur because of the change in frequencies within the system. This is the most important type of amplitude distortion. Though, It happens when there is an input signal given to the components that saturate. And, this causes the clipping if the input exceeds a particular level.
How does it occur?
The harmonic distortion in PCB usually arises because of the use of nonlinear loads. Therefore, due to the surplus use of such loads, the existence of these distortions in the current and voltage waveforms has increased. Since the nonlinear loads change the impedances in the input voltage. Hence, this brings the distortion at the output voltage or current.
Effect of Harmonic Distortion
Due to the harmonic distortion, the Printed circuit Board gets heat up. As a result, the output of the circuit does not appear equals to the input of the circuit. And, this is harmful to any circuit. Because it can cause power loss and overheat the board. To overcome that heating the board requires the heat sink too. Thus, increases the cost of PCB. Also, it decreases the reliability and durability rate of the Printed circuit boards.
How to Reduce Harmonic Distortion
When there is a problem, there is always a solution for that problem. So, harmonic distortion can also be reduced. I can’t be completely diminished. But, it can be lessened by some techniques:
- Board Layout: Higher frequency currents return to the small bypass capacitors. While the lower frequency signals return to the large bypass capacitors. Lower frequency signals may also ignore the bypass capacitor and directly flow to the supply wiring. To protect ground paths, use ground points and ground capacitors on the output side if possible. Try to place a high-frequency bypass capacitor as close to the supply pins as possible.
- Add 0.15 Inches of Trace: The above technique can not improve a lot in distortion. Hence, the real improvement occurs by adding 0.15 inches of the trace to the high-frequency bypass connection.
