AustriamicrosystemsAS3400单路环境噪音消除（ANC）解决方案
2012-01-31
作者：Austriamicrosystems公司
</a>环境噪音消除" title="环境噪音消除">环境噪音消除" title="环境噪音消除">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：
http://www.austriamicrosystems.com/content/download/143123/756655/85634
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：
http://www.austriamicrosystems.com/content/download/143123/756655/85634
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