Austriamicrosystems AS3400单路环境噪音消除（ANC）解决方案
发布时间：2012-1-30 14:50
发布者：1770309616
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Austriamicrosystems公司的AS3400/10/30集成了环境噪音消除（ANC）功能的扬声器放大器，能降低本底环境噪音，提高了手持设备，耳机，语音通信设备等的音频质量。ANC处理的带宽10Hz~2000Hz，噪音降低10dB-30dB，主要用于耳机，手持设备，手机，免提卡和语音通信设备。 AS3400/10/30扬声器驱动器具有手机、耳机的环境降噪功能。它的目的是，通过减少背景环境噪音，提高声音质量，例如，听音乐、电话交谈时。 其全方位的模拟，使功耗降低，系统BOM成本也降低，具有自然的语音增强。这在DSP的环境中是难能可贵的。该器件的设计合理，可以很容易地应用到现有的架构上。 
图1 AS3400反馈方框图 其内部的OTP-ROM可以根据需要，用来存放麦克风增益校准设置。 AS3400/10/30可以用在不同的配置中，以协调噪音消除，过滤功能，和构造设计。该设计采用了简单的，前馈拓扑结构，有效地减少了低频背景噪声。其反馈拓扑以及1或2个过滤级，可用于较大的频率范围，以减少噪声，甚至可以实施传输功能，如，扬声器均衡，Baxandall均衡，高/低搁置过滤，和设置一个预定义的环路带宽。通过特定尺寸的，简单的R，C元件，用户优化了过滤器回路，以用于特定的手机和构造设计。 
图2 AS3430反馈应用案例电路图 大多数手机实现将一个单一的噪音检测麦克风的使用。两个麦克风，可以用来让手机机械设计的灵活性，增加他们的位置。使用桥接模式，允许甚至推动高阻抗耳机。 AS3400/10/30主要特性 •麦克风输入 – 128增益步骤@0.375dB，静音，带有AGC –差分，低噪音的麦克风放大器 –单端或差分模式 –极体传声器改进电源 –话筒增益OTP编程 –高效率的耳机放大器 – 2×34mW，0.1％THD@16Ω，1.5V电源 –100dB信噪比 –桥接模式，例如300Ω负载 –点击和弹出下启动，模式切换 •线路输入 –通过串行接口或针脚的音量控制 – 64步骤@0.75dB和静音，弹出的增益设置 –单止立体声或单声道差分模式 • ANC处理 –向前取消 –反馈取消滤波器环路传递函数，通过简单的RC组件可定义 –生产，软件校准简单 –12db~30dB的降噪（耳麦依赖） –10Hz~2000Hz宽频有源噪声衰减（依赖于耳机） •监视功能 –辅助的听证，即监测 –固定（OTPPROG），周围的声音放大，以弥补耳机被动衰减 –音量控制环境扩声与固定混合（OTP PROG）衰减LINEIN •增量功能 –在接收路径上有或没有音乐的ANC –改进的动态范围播放 –在生产过程中OTP ROM的自动微调（4倍可编程） •性能参数 – 5/3.8mA@1.5V stereo/mono ANC; <1μA 静态 – 217Hz扩展PSRR 
图3 AS3430差分正馈应用案例电路图 •接口 – 2线串行控制模式及音量输入 –通过Line-In或2线串行接口校准 （专利申请中） –单电池或固定的1.0V~1.8V电源，内部CP •封装 – AS3400, AS3410 QFN24 [4mm×4mm] 0.5mm间距 – AS3430 QFN32 [5mm×5mm] 0.5mm间距 AS3400/10/30应用 该设备是耳片、耳机、免提、移动电话、语音通信设备的较理想选择。 Austriamicrosystems公司的AS3400/10/30集成了环境噪音消除（ANC）功能的扬声器放大器，能降低本底环境噪音，从而提高了手持设备，耳机，语音通信设备等的音频质量。ANC处理的带宽10-2000Hz，噪音降低10-30dB，主要用于耳机，手持设备，手机，免提卡和语音通信设备。本文介绍了AS3400/10/30主要特性，反馈和正馈方框图，反馈应用案例电路图与差分正馈应用案例电路图。 The AS3400/10/30 are speaker driver with Ambient Noise Cancelling function for handsets, headphones or ear pieces. It is intended to improve quality of e.g. music listening, a phone conversation etc. by reducing background ambient noise. The fully analog implementation allows the lowest power consumption, lowest system BOM cost and most natural received voice enhancement otherwise difficult to achieve with DSP implementations. The device is designed to be easily applied to existing architectures. An internal OTP-ROM can be optionally used to store the microphones gain calibration settings. The AS3400/10/30 can be used in different configurations for best trade-off of noise cancellation, required filtering functions and mechanical designs. The simpler feed-forward topology is used to effectively reduce low frequency background noise. The feed-back topology with either 1 or 2 filtering stages can be used to reduce noise for a larger frequency range, and to even implement transfer functions like speaker equalization, Baxandall equalization, high/low shelving filter and to set a predefined loop bandwidth. The filter loop is optimized by the user for specific handset electrical and mechanical designs by dimensioning simple R, C components. Most handset implementations will make use of a single noise detecting microphone. Two microphones could be used to allow for increased flexibility of their location in the handset mechanical design. Using the bridged mode allows to even drive high impedance headsets. AS3400/10/30主要特性： Microphone Input 128 gain steps @ 0.375dB and MUTE with AGC Differential, low noise microphone amplifier Single ended or differential mode Improved supply for electret microphone MIC gain OTP programmable High Efficiency Headphone Amplifier 2x34mW, 0.1% THD @ 16Ω, 1.5V supply, 100dB SNR Bridged mode for e.g. 300Ω loads Click and pop less start-up and mode switching Line Input Volume control via serial interface or volume pin 64 steps @ 0.75dB and MUTE, pop-free gain setting Single ended stereo or mono differential mode ANC processing Feed-forward cancellation Feed-back cancellation with filter loop transfer function definable via simple RC components Simple in production SW calibration 12-30dB noise reduction (headset dependent) 10-2000Hz wide frequency active noise attenuation (headset dependent) Monitor Function For assisted hearing, i.e. to monitor announcements Fixed (OTP prog.) ambient sound amplification to compensate headphone passive attenuation Volume controlled ambient sound amplification mixed with fixed (OTP prog.) attenuation of LineIn Incremental Functions ANC with or without music on the receiving path Improved dynamic range playback OTP ROM for automatic trimming during production (4 times programbable) Performance Parameter 5/3.8mA @ 1.5V stereo/mono ANC; <1μA quiescent Extended PSRR for 217Hz Interfaces 2-wire serial control mode & volume inputs Calibration via Line-In or 2-wire serial interface (patent pending) Single cell or fixed 1.0-1.8V supply with internal CP Package AS3400, AS3410 QFN24 [4x4mm] 0.5mm pitch AS3430 QFN32 [5.x5mm] 0.5mm pitch AS3400/10/30应用： The devices are ideal for Ear pieces, Headsets, Hands-Free Kits, Mobile Phones, and Voice Communicating Devices. 
图1。AS3400反馈方框图 
图2。AS3400前馈方框图 
图3。AS3400前馈ANC方框图 
图4。AS3430反馈应用案例电路图 
图5。AS3430差分正馈应用案例电路图 详情请见： 
AS3400_10_30_Datasheet_EN_v1.pdf
(1.5 MB)
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