Reducing the number of cables saves space and reduces heat dissipation.
Connect the antenna to the head unit with one line

While listening to music or the radio in cars has continued from ancient times to the present, the form of head units has gradually changed. From cassette tapes to CDs and MP3s, as sound sources evolved from records to music, head units have become more streamlined.

Supporting such systems in a car requires tens of kilograms of cable. Cable routing is often manual, time-consuming and costly. Car radios typically require up to six cables, depending on the car model and supported band functions. A streamlined head unit reduces the amount of cable required, saving space and reducing heat dissipation.

Maxim Integrated's "Remote Tuner Solution" is a solution to reduce the amount of cables. This remote tuner architecture serializes the output of a radio tuner located near the antenna onto a single cable using Gigabit Multimedia Serial Link (GMSL). This single cable carries control signals (I2C) on the desired channel as well as the back channel of the GMSL link, and powers the remote tuner.

This architecture eliminates the need for a radio receiver, which complicates head unit layout and adds to thermal issues. Radio designs can also be modularized, so changes to the design can be made only through the remote tuner, without modifying the head unit hardware.

The remote tuner solution utilizes a Software Defined Radio (SDR) architecture, which uses software to perform baseband processing and allows reception of various wireless standards on a single radio platform. A typical radio receiver amplifies the signal received from the antenna through a low-noise amplifier in the front-end section and downconverts it with a mixer. This signal is then filtered, digitized, and transmitted.

To increase efficiency and simplify design, some functions can be implemented in front-end hardware. However, wideband signal processing is advantageously implemented in hardware. To maximize flexibility with SDR, the World Band Radio (WBR) is proposed as a standalone front-end tuner capable of implementing major analog and digital radio standards. A typical automotive radio uses three WBR tuner ICs, each serving various purposes, including main station, alternate frequency search, and phase.

The MAX2175 IC is an analog/digital hybrid radio receiver with an RF-to-Bits front-end for SDR solutions in automotive reception environments. It features a single hardware platform supporting global radio standards and can be updated to meet different standards through software changes, rather than requiring hardware rework.

This software-defined radio approach eliminates the need for a dedicated baseband processor, providing users with greater flexibility. Its modular design allows for installation anywhere in the vehicle. The number of cables required is reduced from four to two, reducing cable loss from antenna to tuner, eliminating the need for a low-noise amplifier.

“The MAX2175 was created based on market needs,” said Choi Young-kyun, director of Maxim Integrated Korea. “Maxim’s tuner architecture reduces transmission loss, lowers cost, and saves space.” He added, “Depending on the OEM, the antenna structure they request varies. Maxim proposes a method to transmit the signal from the antenna to the head unit in a single line. This method can solve both signal loss and power issues.”