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Noise-cancellation speaker driver ICs produce zero audible hiss

Noise-cancellation speaker driver ICs produce zero audible hiss

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By eeNews Europe



The AS3435, for feedback systems, and AS3415, for feed-forward systems, incorporate ultra-low noise amplifiers with a 900 nV input referred noise floor: the devices are the first ANC speaker drivers to produce no audible high-frequency hiss when paired with low-noise microphones.

This means that manufacturers of audiophile products can replace existing ANC solutions with the AS3435 and AS3415 to provide users with an improved listening experience, benefiting from the devices’ audio characteristics including 35 mW stereo output power with THD+N of 0.1% into a 32Ω load and a typical signal-to-noise ratio of >110 dB.

These ANC ICs also provide for improvements to the mechanical design of a headset’s housing. Conventional ANC headsets require a mechanical switch, to activate a bypass mode. When the headset’s battery is completely discharged, the user must bypass the noise cancellation function in order to continue listening to music via the Line In channel. The need to accommodate this switch constrains the design of the headset’s housing and circuit board.

The AS3435 and AS3415 feature integrated bypass switches, so that the music signal coming from the 3.5 mm audio jack may be routed through the ANC chipset without any power source connected to the device. By eliminating the external switch, this feature helps to reduce bill-of-materials cost and the size of the PCB, as well as relieving the designer of the need to accommodate a mechanical switch on the headset’s housing.

At the same time, the devices’ analogue implementation of noise cancellation provides for power consumption often two or three times lower than equivalent digital solutions. Featuring typical power consumption of 10 mW at 1.5V in noise cancellation mode, either device can support operation for more than 100 hours from a single AAA battery.

ams has supported the introduction of the AS3435 and AS3415 ANC ICs with the release of an improved design tool, enabling development of the filter networks that match the operation of noise cancellation to the sonic characteristics of the headset design. The graphical interface of the Windows-based tool can display the entire signal chain across the user’s screen, and provides a SPICE module for simulating the operation of filter architectures. In the AS3435 and AS3415, ams has also added a new bass boost equalisation capability, eliminating the need for a discrete signal processing IC to perform equalisation functions.

The AS3435 feedback ANC IC is priced at $3.90 (1,000) pieces. The AS3415 feed-forward ANC IC is priced at $3.50; AS3435 is in a QFN36 package, and the AS3415 in a QFN32 package, both 5 x 5 mm. An evaluation kit for the AS3435 and AS3415 is available online.

Ams; www.ams.com/ANC/AS3415 / www.ams.com/ANC/AS3435

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