Analog Active Noise Canceling Headset

Analog systems to achieve active noise cancellation in headphones were designed and implemented. Our project addresses two distinct technqiues feed forward and feedback systems. The work up to mid-semester, which was focused mainly on a feed-forward system with the motivation of developing a clip-on platform for generic earphones, is presented briefly. Limitations of this approach that lead to a poor noise cancellation figure (5-10 dB) are identified. Subsequently, feedback-based noise cancellation methods based on analog circuits as well as DSP are studied. As the central goal of this project, we focus on the design of an analog feedback control system based on cascade compensation. After identifying the plant frequency response, a suitable compensation network comprising lag and lead circuits was designed. In theory, the design aims to achieve a maximum noise cancellation of 20 dB at 100 Hz while simultaneously maintaining good stability margins, which are essential due to high plant variability. Circuits for implementing the compensator were designed and characterized. The performance of the entire closed loop system is then evaluated in terms of noise cancellation figures and frequency response of the music input. We achieved a maximum noise cancellation of 17 dB at 100 Hz and an improvement in the headphone response for bass inputs.