|
Austriamicrosystems公司的AS3400/10/30集成了環境噪音消除（ANC）功能的揚聲器放大器，能降低本底環境噪音，提高了手持設備，耳機，語音通信設備等的音頻質量。ANC處理的帶寬10Hz~2000Hz，噪音降低10dB-30dB，主要用于耳機，手持設備，手機，免提卡和語音通信設備。 AS3400/10/30揚聲器驅動器具有手機、耳機的環境降噪功能。它的目的是，通過減少背景環境噪音，提高聲音質量，例如，聽音樂、電話交談時。 其全方位的模擬，使功耗降低，系統BOM成本也降低，具有自然的語音增強。這在DSP的環境中是難能可貴的。該器件的設計合理，可以很容易地應用到現有的架構上。 
圖1 AS3400反饋方框圖 其內部的OTP-ROM可以根據需要，用來存放麥克風增益校準設置。 AS3400/10/30可以用在不同的配置中，以協調噪音消除，過濾功能，和構造設計。該設計采用了簡單的，前饋拓撲結構，有效地減少了低頻背景噪聲。其反饋拓撲以及1或2個過濾級，可用于較大的頻率范圍，以減少噪聲，甚至可以實施傳輸功能，如，揚聲器均衡，Baxandall均衡，高/低擱置過濾，和設置一個預定義的環路帶寬。通過特定尺寸的，簡單的R，C元件，用戶優化了過濾器回路，以用于特定的手機和構造設計。
圖2 AS3430反饋應用案例電路圖 大多數手機實現將一個單一的噪音檢測麥克風的使用。兩個麥克風，可以用來讓手機機械設計的靈活性，增加他們的位置。使用橋接模式，允許甚至推動高阻抗耳機。 AS3400/10/30主要特性 •麥克風輸入 – 128增益步驟@0.375dB，靜音，帶有AGC –差分，低噪音的麥克風放大器 –單端或差分模式 –極體傳聲器改進電源 –話筒增益OTP編程 –高效率的耳機放大器 – 2×34mW，0.1％THD@16Ω，1.5V電源 –100dB信噪比 –橋接模式，例如300Ω負載 –點擊和彈出下啟動，模式切換 •線路輸入 –通過串行接口或針腳的音量控制 – 64步驟@0.75dB和靜音，彈出的增益設置 –單止立體聲或單聲道差分模式 • ANC處理 –向前取消 –反饋取消濾波器環路傳遞函數，通過簡單的RC組件可定義 –生產，軟件校準簡單 –12db~30dB的降噪（耳麥依賴） –10Hz~2000Hz寬頻有源噪聲衰減（依賴于耳機） •監視功能 –輔助的聽證，即監測 –固定（OTPPROG），周圍的聲音放大，以彌補耳機被動衰減 –音量控制環境擴聲與固定混合（OTP PROG）衰減LINEIN •增量功能 –在接收路徑上有或沒有音樂的ANC –改進的動態范圍播放 –在生產過程中OTP ROM的自動微調（4倍可編程） •性能參數 – 5/3.8mA@1.5V stereo/mono ANC; <1μA 靜態 – 217Hz擴展PSRR
圖3 AS3430差分正饋應用案例電路圖 •接口 – 2線串行控制模式及音量輸入 –通過Line-In或2線串行接口校準 （專利申請中） –單電池或固定的1.0V~1.8V電源，內部CP •封裝 – AS3400, AS3410 QFN24 [4mm×4mm] 0.5mm間距 – AS3430 QFN32 [5mm×5mm] 0.5mm間距 AS3400/10/30應用 該設備是耳片、耳機、免提、移動電話、語音通信設備的較理想選擇。 Austriamicrosystems公司的AS3400/10/30集成了環境噪音消除（ANC）功能的揚聲器放大器，能降低本底環境噪音，從而提高了手持設備，耳機，語音通信設備等的音頻質量。ANC處理的帶寬10-2000Hz，噪音降低10-30dB，主要用于耳機，手持設備，手機，免提卡和語音通信設備。本文介紹了AS3400/10/30主要特性，反饋和正饋方框圖，反饋應用案例電路圖與差分正饋應用案例電路圖。 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應用： The devices are ideal for Ear pieces, Headsets, Hands-Free Kits, Mobile Phones, and Voice Communicating Devices.
圖1。AS3400反饋方框圖
圖2。AS3400前饋方框圖
圖3。AS3400前饋ANC方框圖
圖4。AS3430反饋應用案例電路圖
圖5。AS3430差分正饋應用案例電路圖 詳情請見： 
AS3400_10_30_Datasheet_EN_v1.pdf
(1.5 MB)
|
