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Power Electronics

Microtune amplifier chip for in-glass or small roof antennas

Microtune Inc. has launched a single-chip AM/FM amplifier, MT1120, for integration into vehicle window-mounted antennas, small roof antennas or other integrated antenna systems. It amplifies 0.15 MHz to 6.2 MHz AM and 76 MHz to 162.4 MHz radio signals to compensate for the reduced performance of in-glass or small roof-mount antennas, and can be used in both single-antenna systems, and in antenna diversity systems, which require multiple amplifiers to support multiple antennas.

Barry Koch, vice president and general manager of Microtune's Automotive Business Unit, says the chip integrates an FM amplifier, AM amplifier, and automatic gain control (AGC) functions for the FM and AM bands. External PIN diodes can be used to set AGC thresholds according to the application requirements. An on-chip temperature-compensated reference generator and high-output voltage op-amp combine to form a power supply that can be connected directly to a non-regulated automotive electrical system.

Sophisticated design technology allows the AM amplifier to achieve low noise, very low distortion, and high-input impedance, and to drive very low-output impedance, according to Koch. The FM amplifier is matched to 50 ohms and is designed for low noise and very low signal distortion. “These characteristics are required for achieving high-end AM/FM system performance, particularly under critical reception conditions,” he says.

"Automotive suppliers are rapidly expanding the use of integrated antenna systems in automobiles across an increasing number of makes and models," he adds, suggesting that the MT 1120 permits system providers to match varying antenna structures with different radio configurations. The chip also conforms to the applicable specifications of major worldwide carmakers and can be used across global markets.

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