ICs Deliver Feed-Forward, Feedback Noise Cancellation

The AS3501 and AS3502 provide receive-path active noise-cancelling solutions. The AS3501 is a highly integrated cost-competitive IC for feed-forward noise cancellation, and the AS3502 enables active noise cancellation for feedback applications where the microphone is acoustically close to the loudspeaker. Both units operate from a single 1.0- to 1.8-V supply and combine true ground headphone amplifier stages with flexible noise-cancelling architectures. This reduces the bill of materials by at least 60%. Internal user-definable register settings allow different device configurations that permit product differentiation and flexibility. The ICs provide up to 34 mW in single-ended mode and over 100 mW in BTL mode into 16-O loudspeakers from a 1.5-V supply. The devices ensure greater than 100 dB SNR and less than 0.1% total harmonic distortion. The AS3501 comes in a 24-pin 4- by 4-mm QFN package and the AS3502 comes in a 32-pin 5- by 5-mm QFN package. Both have operating temperature ranges of ?20°C to 70°C. AUSTRIAMICROSYSTEMS AG, Unterpremstaetten, Austria. (408) 345-1790.