“Amplifier shipment growth in the smart phone market is due not only to an increase in stereo sound in high-end phones but also the mid-tier market, defined as phones priced between $200 and $500,” said SAR Insight principal analyst, Peter Cooney. “We anticipate this growth to continue with an estimated increase from the 500 million amplifiers shipped into mid-tier phones in 2017, to almost 700 million by 2022.”
In response to this, Cirrus Logic has introduced a smart power amplifier, designed to support the trend of stereo audio in smartphone and portable devices.
The CS35L41 is an 11-volt boosted Class D audio amplifier with DSP, complemented with Cirrus Logic’s SoundClear Playback software. According to Cirrus, it improves audio quality and increases the loudness of smartphone speaker output, while protecting the speaker using both hardware and software techniques.
The core of the CS35L41 features a 5.3-watt digital input, mono Class D amplifier with the lowest noise and idle power consumption in its class. An integrated 11-volt Class H DC-DC converter boosts the supply voltage and maintains higher efficiency than other audio power amplifiers relying on Class G boost regulators, says Cirrus. By adaptively tracking the audio level, the Class H boost converter helps improve system efficiency, minimises power dissipation and preserves battery life.
Cirrus Logic’s SoundClear Playback software provides the ability to fine tune audio to the specific micro speaker being used in the mobile system. Equalization, compression and psychoacoustic enhancement algorithms improve sound clarity and increase loudness. Playback filtering compensates for the unique frequency response of the speaker, while eliminating pre-ringing found in conventional linear phase filters.
Its battery management system and predictive algorithms adapt to changing audio, speaker and battery conditions to minimise power consumption and battery current, without sacrificing audio performance. Its low 6.7-milliwatt (mW) quiescent current also contributes to battery preservation.
This amplifier uses 55 nm process technology, the most advanced for this class of amplifiers, claims Cirrus, resulting in a 5.64 mm2 space-saving WLCS package. This is important to OEMs who want to include a two-speaker design, as well as pack in as many new features and functions as possible, adds Cirrus.