As ViVo, Xiaomi and other domestic mobile phone brands have announced their high-profile entry into the Hi-Fi era, the battlefield of the mobile phone circle has begun to expand into the field of high-quality audio playback. In fact, this is where analog / mixed-signal chip manufacturers have been cultivating for many years. Signal chain solution providers like ADI have been supplying chips to major audio equipment manufacturers for many years. In the audio equipment around you, there may be ADI Inside.
The history of audio processing is a process in which people continue to reproduce nature. From the birth of the first recording device in 1859 to the advent of Dolby Blu-ray HD audio in 2006, the quality of the audio became closer to the original sound. The audio player has also made a rapid transition from analog technology to digital technology.
Stephen Wu, Marketing Manager, Consumer Products Division, ADI Asia, introduced that the current audio equipment has two major development trends, one is represented by WiFi and Bluetooth, and the other is portable equipment. These two points ADI is very concerned.
The mobile phone can be considered as an integrator of these two trends, so the audio processing on the mobile phone has developed to a new level. Especially this signal link from the processed sound to the headset or the external speaker is the focus of smart phones to achieve Hi-Fi sound quality. Wu Yanbin introduced that in the design of current smartphones, two-stage amplification circuits can be connected behind the DAC to drive the headphones. For example, the first stage converts the current into a voltage, and the second stage amplifies the voltage to achieve dual-channel and high sound quality .
In this part, ADI has a complete solution, implemented with DSP ADAU1452, stereo class D amplifier SSM3582, and operational amplifier AD4841 or AD4896.
The ADAU1452 is a DSP that includes a CODEC and was originally designed for the automotive market and complies with automotive specifications. It has fully programmable enhanced sound processing capabilities, 1.2V 32-bit SigmaDSP® processing core operating frequency of 294.912MHz, each sampling rate of 48kHz, more than 6144SIMD instructions. Its audio processing algorithm uses a sample-by-sample and block-by-block mode, which can be used in the signal processing process at the same time.
Why put automotive-grade DSP products into the consumer electronics market? Zhao Chuanyu, sales manager of ADI's communications and consumer customer division, said that there are still differences between products that are put into the automotive and consumer markets. However, this product can pass rigorous automotive tests and has no pressure in the consumer market. Most importantly, the audio needs of car stereos and consumer electronics are essentially the same.
In fact, ADI has clear product divisions for different requirements of the audio market. Used in the high-end is the SHARC® DSP, used in the high-end is the Blackfin® DSP family, used in the mainstream product is the ADAU145x series, the entry-level by the ADAU17xx.
The SHARC series has floating-point arithmetic functions, excellent core and memory performance, and excellent I / O throughput. It can do sound analysis, compensation, and sound effect changes. Many international brands OEM and ODM use it for design. ADAU1452 belongs to SigmaDSP® and is a series specially optimized for audio. Although there is no floating point operation function, the operation speed is very fast. It is very convenient to realize the design of audio link with the graphics programming tool SigmaStudioTM.
Must mention SigmaStudioTM here, this is a graphical programming tool with great functions. It has huge resources, users can select the desired dynamic processor, mixer, DSP, filter, and drag and drop directly to complete the design.
According to Wu Yanbin's introduction, SigmaStudioTM is widely used in the design of car audio. Because the combination of components inside the car is very complicated, it will cause different actual sound effects. Using SigmaStudioTM, calling different components for testing is simple and convenient. SigmaStudioTM can meet product development from low-end to high-end. Many steps after hardware design can be implemented with it. For example, the width of the sound field can be used for debugging.
In this scheme, the class D amplifier SSM3582 is also very important. Because the digital signals processed by the DSP are converted into analog signals via it. The quality of the conversion directly affects the sound quality. SSM3582 has the highest SNR, lowest THD, and very low quiescent current on the market. These are the key to ensuring high sound quality.
As mentioned earlier, the two-stage amplification can be used to drive headphones. ADI's AD4841 and AD4896 are ideal for preamplification. The AD4841 can make the sound without obvious defects and achieve a predefined timbre, while the AD4896 can express a cheerful, delicate and highly penetrating human voice. Why the "personality" of these two products is so obvious, because "the requirements of the two levels are not the same for the op amp. The first level is usually more concerned with the performance indicators. It is necessary to make this performance as good as possible. To improve the ratio, the second level of driving ability is the key, â€Zhao Chuanyu explained.
ADI, a complete set of audio processing solutions, is based on its own deep accumulation and is in a leading position in the domestic mobile phone audio market. Currently, seven of the top ten mobile phone manufacturers in China use ADI solutions. The market situation can be described as good, but what will ADI think of the continued trend of this mobile phone audio processing upgrade?
In this regard, Zhao Chuanyu believes, "From the perspective of indicators, whether it is vivo's flagship product or the newly released Xiaomi note, it can achieve the level of entry-level music players in the main indicators. The price is four digits, but now you can enjoy this effect on mobile phones. Therefore, from the perspective of technological evolution, it is foreseeable that portable music players should soon be eliminated by mobile phones. "
He also emphasized, "Some mobile phone manufacturers such as Apple and Samsung did not introduce Hi-fi, which does not mean that this is not the development trend of technology. As long as each manufacturer finds a correct positioning, there can be a good market. Seeing many manufacturers Hi-fi is a selling point, from this point I am very optimistic about its prospects. "
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