D类功放中输入斩波运放电路的设计  

Design of Input Chopper OP Used in Class D Amplifier

作　　者：赵海亮[1] 刘诺[1] 周长胜[2] 

机构地区：[1]电子科技大学微电子与固体电子学院,成都610054 [2]中科院嘉兴中心电子设计与应用分中心,浙江嘉兴314000

出　　处：《半导体技术》2008年第6期520-523,538,共5页Semiconductor Technology

基　　金：浙江省引进消化吸收再创新重大项目基金(2006C14036)

摘　　要：基于n阱0.5μmDPDMCMOS工艺,完成了D类音频功放中输入斩波运算放大器的设计。分析了D类系统对输入运放的设计要求,在此基础上确定了电路采用两级全差分结构实现,并加入斩波结构降低噪声。采用PTAT电流源提供运放的偏置电流,补偿运放跨导gm的温度漂移。在Cadence下的电路仿真表明,前级运放具有16μV.Hz-1/2的等效输入噪声,开环增益达到117.3 dB。运放所在芯片经过PWM方式流片验证,测试结果显示,芯片THD达到0.58%(f=1 kHz、Po=1 W、VDD=5 V),电源抑制比为65 dB。The input chopper OP used in class D audio amplifier was presented based on n well 0.5 μm DPDM CMOS technology. The design requirement of input OP in Class D system was analyzed, based on which a two-stage fully differencial structure was realized and the chopper structure was used to reduce the noise. PTAT current source served for the bias current of the OP for compensation of the temperature excursion of gm. The circuit simulation in cadence shows that the input amplifier has input referred noise power of 16 μV·Hz^-1/2, the open gain reaches 117.3 dB, the chip including the input OP is validated by PWM tape out, and the results show that THD reaches 0.58% （f = 1 kHz, Po = 1 W, VDD = 5 V）, the power supply rejection ratio is 65 dB.

关 键 词：D类功放 斩波 输入运放 跨导温漂 

分 类 号：TN432[电子电信—微电子学与固体电子学]