A Low-Power Broad-Bandwidth Noise Cancellation VLSI Circuit Design for In-Ear Headphones

Abstract

Conventional active noise cancelling (ANC) headphones often perform well in reducing the low-frequency noise and isolating the high-frequency noise by earmuffs passively. The existing ANC systems often use high-speed digital signal processors to cancel out disturbing noise, which results in high power consumption for a commercial ANC headphone. The contribution of this paper can be classified into: 1) proper filter length selection; 2) low-power storage mechanism for convolution operation; and 3) high-throughput pipelining architecture. With these novel techniques, we develop an area-/power-efficient ANC circuit by using the TSMC 90-nm CMOS technology for in-ear headphone applications. The proposed feedforward filtered-x least mean square ANC circuit design provides the features of using lower operating frequency and consuming much less power that facilitate better performance than the conventional ANC headphones. To verify the effectiveness of the proposed design, a series of physical measurements is executed in an anechoic chamber. Measurement results show that the proposed high-performance/low-power circuit design can reduce disturbing noise of various frequency bands very well, and outperforms the existing works. The proposed design can attenuate 15 dB for broadband pink noise between 50 and 1500 Hz when operated at 20-MHz clock frequency at the costs of 84.2 k gates and power consumption of 6.59 mW only. Compared with the existing designs, the proposed work achieves higher noise cancellation performance in terms of 3 dB further and saves 97% power consumption.