Electronic circuit design for audio noise elimination

As we all know, today?s converged portable multimedia devices have more and more features integrated into their smaller systems. Audio is a basic feature of any system marketed with multimedia capability. Engineers often put more focus on portable multimedia devices that have features such as wireless connectivity, video processing, image capture and display. Hence, audio circuits end up wedged in the system wherever space can be found among other components, resulting in mediocre or downrigth poor audio quality.There are many sources of poor audio quality in portable audio systems, but this thesis focuses on sources of audible noise on analog audio signals. Non-harmonically related noise, whether white(flat) or tonal, can be very annoying to the end user. White noise is perceived as a background hiss, which is very noticeable during quiet audio passages. Tonal noise can be perceived as a buzz, hum or whine, depending on the frequency content.Audio noise can be encountered in all audio visual equipment such as televisions, dvd players, home theatre systems etc. Although there are different techniques used to reduce the audible noise and to increase the audio quality in such systems, designing a system that is totally silent is almost impossible. In this thesis, a new technique is proposed to prevent the audio noise in portable audio equipments. This new technique is based on a circuit mounted on the motherboard of the equipment and it is intended to prevent extraneous noises emanating from speakers. The designed circuit is implemented on an LCD(Liquid Crystal Display) television and has reduced the audio noise significantly.