Nowadays, the automotive infotainment system fully embodies the innovative and excellent automobile engineering technology. The system has evolved from the original car radio into a comprehensive multimedia car electronics that integrates audiovisual entertainment, vehicle communication, navigation, network control and other functions. 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.
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 a proprietary intellectual property algorithm, the ConTInues 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 (adapTIve-array-antenna, AAA) technology, and 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
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