Today's automotive infotainment system fully embodies innovative and superior automotive engineering technology. The system has evolved from the original car radio into a comprehensive multimedia car electronics that integrates audiovisual entertainment, in-vehicle communication, navigation, and network control. system. Tuners and audio digital signal processors (DSPs) have played an important role in this evolution. In addition to providing a variety of power solutions for automotive infotainment applications, ON Semiconductor also develops and delivers advanced tuner and audio DSP solutions by integrating its expertise in automotive systems, multimedia and communications, and a wealth of intellectual property modules. Support all current and future comprehensive features that help improve the driving experience.
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Tuner classification and ON Semiconductor tuner solution
A car tuner is an in-vehicle device for receiving FM/AM broadcasts, which is divided into an analog tuner, a digital tuner, and a data tuner. The analog tuner is a traditional system on-board tuner for basic models; the digital tuner is suitable for digital radios for medium and high-end models, with higher signal reception quality and easier use, becoming the current trend; data tuner can receive Traffic information, wireless data broadcasting system (RDS) / China Real-Time Traffic Information (RTIC), adapt to all models.
In actual use, if the same FM broadcast signal arrives at the receiving terminal at different times, multi-channel distortion noise is generated. ON Semiconductor's DSP tuner uses the proprietary intellectual property Continuous Modulus Algorithm (CMA) technology to dramatically reduce multi-channel noise. ON Semiconductor also has another intellectual property for multi-channel noise, the proven dual-tuner adaptive-array-antenna (AAA) technology, with plans to introduce follow-up products.
Specifically, the CMA is a multi-channel noise suppression technique for a single tuner. Compared with the traditional technology, the additional feedback type can avoid the occurrence of false ghosts, and greatly improve the multi-channel noise convergence speed under various conditions; the change of the evaluation function/coefficient update formula greatly improves the convergence speed, effectively preventing FB Side divergence. The actual test confirmed the effect of improving the noise immunity.
Figure 1: CMA improves noise immunity
Figure 2 compares the multichannel noise cancellation performance of CMA and AAA technologies with conventional single tuner. The vertical axis on the left is the number of occurrences of impulse noise per minute, and the vertical axis on the right is the noise intensity. Obviously, ON Semiconductor's single tuner technology can significantly reduce multi-channel noise, and dual tuner AAA technology can almost completely eliminate multi-channel noise. .
Figure 2: Comparison of CMA and AAA technologies with traditional technologies
In addition, thanks to the low-IF technology, compared to traditional tuner circuits (Figure 3), ON Semiconductor's DSP tuner circuitry significantly reduces peripheral circuitry. Compared with the traditional analog tuner, 52 peripheral components are greatly reduced, including VCO coil, varactor diode, FM adjustment coil, ceramic filter, IF adjustment transformer, PIN diode, FM MOSFET, AM j-FET.
Figure 3: DSP tuner circuit is significantly smaller than traditional tuner
Figure 4 is a block diagram of an ON Semiconductor DSP tuner. As can be seen from the figure, the analog front end is a newly designed new design LNA and MIX, which can operate at low voltage and only needs 5 V power supply; the digital back end can support the broadcast interface. The DSP uses the CMA algorithm and has an HD mixing function.
Figure 4: ON Semiconductor DSP tuner block diagram for the China RTIC standard ON Semiconductor tuner solution
RTIC (Real-time Traffic Information of China) is China's unique taxi traffic management and road information collection system, including traffic information center, road information feedback system and road information broadcasting system. The road information feedback system forms real-time RTIC information through the road condition information fed back by the taxi, and then broadcasts it. The system was first established during the Beijing 2008 Olympic Games and has been applied in 22 cities. ON Semiconductor offers the corresponding tuner and solution for the terminal part.
ON Semiconductor's audio processing DSP and CD servo/codec DSP
These schemes use DSP to perform digital calculations. Compared with analog signal processing using discrete devices, they have the advantages of no distortion and simple setup. The disadvantage is that the algorithm is relatively complicated.
In order to achieve sound processing, it is necessary to understand the role of the audio DSP equalizer (EQ). The equalizer has a gain and filtering circuit, and the gain circuit boosts (Boost) and weakens (Cut) the sound; the filter circuit can adjust to the required frequency response. A normal analog sound processing IC can generally provide 2 bands (Bass/Treble) or 3 bands (Bass/Middle/Treble), and a digital sound processing IC can provide multiple frequency bands, such as 7 bands, or even more. Figure 5 is a plot of the 3-band EQ.
Figure 5: Curve of the 3-band EQ
ON Semiconductor's audio processing DSP provides a variety of algorithms, as shown in Table 1.
Table 1: ON Semiconductor's audio processing DSP algorithm
The left table is a list of basic functions, including S3S, AViSS, and New S-Live, which are ON Semiconductor's own algorithms that are available to customers free of charge; the right side is an algorithm to choose from, requires authorization, or requires development costs when changing. These include the industry-renowned SRS CS Auto and Dolby DAEP algorithms, while Bongiovi DPS is the most advanced sound processing technology. ON Semiconductor is currently the only IC partner of the technology.
The audio DSP resources provided by ON Semiconductor include 24-bit dual-core DSP with processing capacity up to 220MIPS, 24-bit ADC/DAC and 760k flash, 8 analog inputs, 5 digital inputs, and 6 analog outputs and 6 digital Output. Powerful hardware resources for better sound processing and true 5.1 channel.
The important function of CD DSP is to control the coordinated action of the various components of the movement and correctly read the data on the disc. ON Semiconductor's CD servo DSP can support CDDA/MP3/WMA/AAC decoding and electronic anti-seismic function.
ON Semiconductor's newly developed DSP inorganic core solution includes various audio format codecs and can support a variety of external devices such as USB, iPad, iPhone, SD card and Bluetooth. The internal algorithm also includes the sound processing function; in addition, the CD-DSP interface is reserved, and the CD movement is used as an optional configuration to achieve platform design. At present, corresponding products have been introduced. Figure 6 shows the inorganic core DSP solution from ON Semiconductor.
Figure 6: ON Semiconductor's inorganic core DSP solution
in conclusion
Using innovative and high-performance technologies and products, ON Semiconductor provides feature-rich tuner and audio DSP products for automotive infotainment systems, as well as energy-efficient power solutions that help meet high performance and better user experience. Engineers reduce power and cost, simplify the design process, and speed time-to-market.
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