| Recent advances in semiconductor technology have renewed interest in Class-D audio amplifiers, especially for portable devices, and consumer electronics.This paper presents a single chip stereo class D amplifier which use a double-sided natural sampling controlled quartenary pule width modulation scheme to achieve very low quiescent current, so that we can improve system efficiency at low input to 90%. At the same time, lower the THD to 0.03%. Furthermore, use special designed second order feedback loop to widen system bandwidth, so that we can get a flatband response between 20 Hz and 20 kHz.The primary work in this thesis is listed as follow:1. Considering both cost and performance demand, we select the 0.6μm standard process delivered by Hynix Inc., achieving optimazed efficiency performance and very high output power. We carefully analysis and calculate the output stage to assure system's safety operation under this process.2. We analysis and calculate the existing sampling process and desgin a double-sided natural sampling controlled quartenary pulse width modulation scheme as the coral technology, improving the system linearity and lowering the quiescent current tremendously.3. Design second order feedback loop to widen system bandwidth. Establish system's transfer function; use MATLAB to analysis system linearity and stability. Calculate system THD by Simulink simulation tool.4. Select and design an operation amplifier of fully differential architecture as the coral operation amplifier, which is achieving higher integration and removes the need for input coupling capacitors.5. Finish all the design and simulations in detail of the whole device. Finish the layout, process and evaluation. The product has efficiency as high as 90% and THD as low as 0.03%.It has outstanding performance, and it can be widely used for kinds of portable audio devices with internal speakers. It's really needed by portable device market. |
PDF Full Text Request