Traditional radio architecture brings many challenges to vehicle designers. Thus, by using the remote tuner solution developed by Maxim Integrated Products, designers can significantly simplify the head unit design of a vehicle and reduce cables. The vehicle’s complex head unit must accommodate multiple tuners, manage heat dissipation and receive multiple cables from the antennas. In addition, the received analog signals pick up noise as they travel from the antenna to the head unit of the vehicle. Finally, baseband processing uses single purpose hardware, requiring separate designs to support multiple worldwide radio standards.

MAX2175-block-diagram(cr) Figure 1: The resulting I-channel and Q-channel data words are transferred to the baseband through an industry standard I²S digital interface.  
The MAX2175 RF to Bits tuner within the solution eliminates the need to rework the vehicle’s hardware to support worldwide radio standards, allowing updates by simply changing the vehicle’s software. This highly integrated tuner uses direct-conversion for DAB and DMB applications, covering both VHF Band-III and L-Band. Reception of FM, DRM+, FM-HD and Weather-Band is supported using a low-IF and digital conversion to baseband. AM (long, medium and short wave) and DRM reception is supported using direct sampling and digital conversion to baseband.

With Maxim’s remote tuner solution, the RF to Bits tuners are now located in a quieter environment close to the antenna to minimise noise. Meanwhile, the digital outputs of the tuners are serialised using Maxim’s gigabit multimedia serial link (GMSL) serialiser and deserialiser (SerDes) onto a single low-cost coax cable. Power for the remote tuner solution is also delivered on this single cable. Not only does this improve radio performance, but it also reduces the weight of the vehicle to provide better mileage. Removing all tuners from the head unit saves space and reduces both system complexity and heat dissipation in the head unit. In a 4-channel radio, for example, 4W of power can be removed from the head unit. In addition, the MAX2175 allows the baseband processing to be done in software on an automotive SoC, such as the Renesas Electronics R-Car H3 SoC. This software defined radio (SDR) approach enables flexible implementations by eliminating the need for a dedicated baseband processor. By simply changing the software, now any worldwide radio standard can be supported using the MAX2175.