| The digital audio power amplifier, also named class d audio power amplifier, is a pulse modulation amplifier. It has the main difference lies in the work of state power amplifier with the traditional analog amplifier. That is the use of pulse forms of high-speed signals to drive the power switch. Its power MOSFET performs as a power switch and the efficiency of this kind of audio power amplifier can be 100% theoretically. This kind of digital audio power amplifier has been extensively used in cell phone, MP3 player, MP4 player, interphone, etc. where the capacity of battery, the output power as well as the area of the main board are limited. The chips of digital audio power amplifier mainly depend on importation. There will be a bright future and a big market by designing digital audio power amplifier IC which has proprietary intellectual property rights.This paper presents a single-chip digital audio power amplifier IC. It mainly used in mobile phones and interphones to these relatively low quality requirements of electronic products. The proposed digital amplifier IC uses a fully-differential pulse width modulation (PWM) scheme which can realize the filter free design. This design is based on the 0.5um CMOS process, and it has a wide supply voltage (2.5V to 5.5V). A 640mW/160mW maximal output power and 90% efficiency can be achieved with an 8? /32? load and a 5V power supply. The total harmonic distortion (THD) of this amplifier is below 0.1% with 330mW/80mW output power. The quiescent current is less than 0.2uA. And the quiescent power dissipation has been reduced to less than 10mW.The architecture of this paper mainly includes modulation proposal design, system performance analysis, circuits design and simulation etc. Firstly, the market of digital audio power amplifier is analyzed and the assignment of the issue is distributed, the digital audio power amplifier used in small power and limited main board field is focused on. After that, the disadvantage of typical digital audio power amplifier is presented, the fully-differential pulse width modulation scheme is proposed and solution is given. At last, structural analysis system, analysis of figures from the start with the efficiency of power amplifiers, identified the sub-circuit performance requirements, through the circuit structure of the selection and optimization, completed the operational amplifier, a triangle-wave circuit, for comparison, the output level and References such as circuit module design, simulate and test of all the blocks as well as the system. The simulation result shows that this amplifier has the character of high efficiency, low loss, and low THD. |
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