Active Noise Cancellation on a Chip
ams has introduced the AS3421 and AS3422 single chip devices for active noise cancellation (ANC). Featuring integrated speaker drivers, the new devices make it easier to implement ANC in Bluetooth wireless headsets, headphones and earpieces. The ANC circuitry processes external noise sensed by a microphone embedded in the headset and generate a noise-cancelling signal, while amplifying the desired audio signal with very low distortion.
Low power consumption and long battery life are particularly important requirements in wireless headsets, and the all-analogue design of the new chips is more efficient than DSP-based (digital) speaker drivers. The devices draw just 7 mA at 1.5 V in stereo ANC mode, and less than 1 µA in quiescent mode. They also implement an ultra-low power ANC bypass mode when the user selects the playback-only function. The new devices additionally provide differential stereo line inputs to match differential line outputs from typical Bluetooth-based headset systems.
