Reduction of noise induced by power supply lines using phase-locked loop

Area of Science:

• Electrical Engineering
• Physics
• Instrumentation

Background:

• Power-line noise significantly degrades signal quality in sensitive detection systems.
• Existing noise reduction methods may limit measurement bandwidth or effectiveness.
• Accurate signal detection is crucial in advanced scientific instrumentation like scanning tunneling microscopy.

Purpose of the Study:

• To develop and experimentally implement a noise reduction technique for power-line interference.
• To improve the signal-to-noise ratio (SNR) in delicate measurements without bandwidth limitation.
• To demonstrate the versatility of the method across different measurement systems.

Main Methods:

• Utilizing a phase-locked loop (PLL) to generate a synchronized sinusoidal wave and its harmonics.
• Adjusting the amplitude and phase of the generated wave and harmonics.
• Employing operational amplifiers to inject the compensating signal into the measurement signal.
• Applying the method to scanning tunneling microscopy (STM) measurements.

Main Results:

• Significant reduction of power-line noise in experimental measurements.
• Improvement in the signal-to-noise ratio (SNR) without compromising measurement bandwidth.
• Demonstrated enhancement in scanning tunneling microscopy image quality.
• Successful noise cancellation achieved through precise amplitude and phase control.

Conclusions:

• The developed method effectively reduces power-line noise in sensitive signal detection.
• The technique offers a versatile solution applicable to various measurement systems beyond STM.
• Improved SNR and preserved bandwidth are key advantages for scientific data acquisition.