| Summary: | 碩士 === 國立交通大學 === 電機學院電信學程 === 104 === This thesis uses smart TV as the experimental platform to study the interference originating from audio DAC (digital-to-analog converter) ground return currents to audio ADC (analog-to-digital converter) ground through the same return path when the TV operates in the PIP (Picture-in-Picture) mode in witch both the main screen and the background analog TV play video and voice. Increasing the number of vias used for the audio DAC’s non-synchronous frequency-differential currents and go to the ground directly, will reduce the path’s impedance and the induced voltage changes. In addition, separating Audio ADC’s ground path to avoid the common current path and reducing mutual inductance can also minimize the impact of the DAC difference-frequency currents and avoiding interference from Audio DAC sampling noise. These practices can effectively reduce audible noise due to audio DAC noise and switching noise.
In this thesis, we also use ANSOFT HFSS to do simulation. Simulation results indicate that improving the ground and power path return current reduces mutual interference. After improving the current return path in the BGA package, experiment as measurements show that the interference level found in the audio ADC module is significantly reduced by 16 dB.
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