低噪声音频电源电路-Low Noise Audio Powe
abstract: audio application note describes a simple, compact scheme that provides a low noise, low ripple power source for use in audio amplifiers, microphones, headphone amplifiers, codecs and other audio circuits.
免费注册参加在线研讨会，学习如何分析、测量并最终解决音频系统的设计问题 (english only) 。
the circuit shown in the figure below reduces noise and ripple voltage by 40db over the 100hz to 20khz audio range. it provides a clean source of 5v power for driving audio circuits in portable applications such as cellular phones and multimedia notebook computers. most linear regulators reject noise only up to 1000hz or so, and the bulk of a low-frequency passive filter is unwelcome in portable applications.
figure 1. this compact circuit actively compensates for power-supply ripple and noise, providing 40db of attenuation in the 100hz to 20khz audio band.
the circuit shown accepts noisy vcc in the range 4.5v to 6v and produces quiet vcc at a dc level 7% lower. for example, it produces 4.65v at 1a from a nominal 5v source, with only 200µa of quiescent current. the physical layout is very small: one sot23 transistor, one µmax (shrink so-8) op amp, and a few passive components. the largest capacitor is 10µf, and the resistors can be 0.1w or surface-mount 0805 size.
when operating, the circuit acts as a wide-bandwidth buffered voltage follower (not a regulator) whose dc output level is 7% below that of vin. r1 and r3 form a voltage divider that provides the 7% attenuation, and c4 helps to form a 93% filtered replica of vin at the op amp's inverting input. the op amp's small input bias current (25na typical) allows large resistor values for r1 and r3, yet limits the maximum dc error to only 20mv. the result is a lowpass filter with 2hz corner frequency that provides 20db of attenuation at 20hz.
because the op amp's common-mode input range extends from rail to rail, its noninverting input can sample the output voltage directly. the op amp's supply voltage is filtered by r2 and c5, providing lower output impedance and better power-supply rejection for the op amp at high frequencies. this filter's 300hz rolloff augments the op amp's psrr (already impressive at 110db).
a similar article appeared in the january 18, 1996 issue of edn magazine.
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低噪声音频电源电路-Low Noise Audio Powe
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免费注册参加在线研讨会，学习如何分析、测量并最终解决音频系统的设计问题 (english only) 。
the circuit shown in the figure below reduces noise and ripple voltage by 40db over the 100hz to 20khz audio range. it provides a clean source of 5v power for driving audio circuits in portable applications such as cellular phones and multimedia notebook computers. most linear regulators reject noise only up to 1000hz or so, and the bulk of a low-frequency passive filter is unwelcome in portable applications.
figure 1. this compact circuit actively compensates for power-supply ripple and noise, providing 40db of attenuation in the 100hz to 20khz audio band.
the circuit shown accepts noisy vcc in the range 4.5v to 6v and produces quiet vcc at a dc level 7% lower. for example, it produces 4.65v at 1a from a nominal 5v source, with only 200µa of quiescent current. the physical layout is very small: one sot23 transistor, one µmax (shrink so-8) op amp, and a few passive components. the largest capacitor is 10µf, and the resistors can be 0.1w or surface-mount 0805 size.
when operating, the circuit acts as a wide-bandwidth buffered voltage follower (not a regulator) whose dc output level is 7% below that of vin. r1 and r3 form a voltage divider that provides the 7% attenuation, and c4 helps to form a 93% filtered replica of vin at the op amp's inverting input. the op amp's small input bias current (25na typical) allows large resistor values for r1 and r3, yet limits the maximum dc error to only 20mv. the result is a lowpass filter with 2hz corner frequency that provides 20db of attenuation at 20hz.
because the op amp's common-mode input range extends from rail to rail, its noninverting input can sample the output voltage directly. the op amp's supply voltage is filtered by r2 and c5, providing lower output impedance and better power-supply rejection for the op amp at high frequencies. this filter's 300hz rolloff augments the op amp's psrr (already impressive at 110db).
a similar article appeared in the january 18, 1996 issue of edn magazine.
比亚迪元,国产小钢炮suv,百公里加速仅需4.9秒,混动版车型油耗仅2L
7805稳压芯片，7805芯片介绍
英国ARM公司新型处理器允许在单一集群中最多提供8个
诺基亚随时准备并有能力为世界各地的客户提供5G服务
DS32X35带有铁电随机存取存储器的高精度实时时钟(RTC
低噪声音频电源电路-Low Noise Audio Powe
京东方：智能手机LCD面板份额多年保持第一
一文了解OLED屏幕
汽车电子立于环境的安全要素的开发
科普一下烟雾传感器的种类及其应用
什么是超导体？
瑞萨电子面向下一代电子电气架构中不断发展的小型应用，推出全新车用执行器和传感器控制MCU
新金属芯片能提高存储速度百倍
电子管发射机电路图大全（6Pl电子管/调频发射机电路图详解）
如何使用C51单片机中的位域功能
300元蓝牙耳机排行榜、300元左右最具性价比的蓝牙耳机
广和通发布新一代5G FWA解决方案
汽车仪表盘指示灯大全（图解）_汽车仪表盘指示灯详解
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