Microwave Engineering Europe - December 2007 - (Page 33) PRODUCTS 33 300-to-930-MHz RF receiver family automotive qualified for ISM and SRD applications Highly integrated RF receivers from Melexis, the MLX71120 and MLX71121 are automotive qualified ICs with dual RF inputs that have been specifically designed for low cost antenna diversity applications in the unlicensed Industrial-Scientific-Medical (ISM) and Short-Range-Devices (SRD) frequency bands. The low-power ICs can address the European 863 to 870 MHz SRD bands or the ISM bands at 902 to 928 MHz in North America. At the same time the receiver chips are applicable for the lower frequency bands at 315 MHz (e.g. in the US) or at 433 MHz (e.g. in Europe and China). Manufacturers of worldwide equipment for automotive Remote Keyless Entry (RKE) and Tire Pressure Monitoring Systems (TPMS) as well as consumer and industrial system makers benefit through the simplification of their production logistics and the indirect reduction in cost. A simple crystal change adapts the system for different application frequencies. The dual RF input feature allows the user to easily set up an antenna diversity scheme previously found only in high-end wireless systems. This can significantly improve the reliability of the RF communications link by selecting the RF input with the best signal quality. Another interesting feature of both receivers’ is the dual-band approach. This allows switching the RF inputs between two applications, one at 433 MHz and a second at 868 MHz. The MLX71120 receiver features a fully integrated FSK and ASK demodulator. The IC provides the freedom to select an external intermediate frequency (IF) filter, operating at one of the two common frequencies 455 kHz or 10.7 MHz. This way the receiver can be easily adapted to very narrow band or medium bandwidth applications. The sister component MLX71121 also features a fully internal demodulator, and it comes additionally with an on-chip IF filter offering a 230-kHz bandwidth. This means no external IF filter is required for the MLX71121. Both come in a 32-lead QFN package with a 5 mm x 5 mm footprint. No bulky external ceramic filter and discriminator components are necessary. The receivers operate over a wide supply voltage from 2.1 to 5.5 V with a typical current consumption of 6.5 to 11 mA. In standby mode the current draw is below 50 nA. The receiver input sensitivity is as low as -113 dBm for ASK and -112 dBm (MLX71120) and 107 dBm (MLX71121) for FSK signals, respectively. The extended operating temperature range of -40 to +125 °C makes the parts ideally fit for automotive applications such as RKE, TPMS or car alarm systems. Other typical applications for the receivers include security systems, home automation, garage door openers, wireless door bells, baby monitors and wireless headsets. www.mwee.com/204201629 Microwave Engineering ● December 2007 ● www.mwee.com 033_MWEE.indd Sec1:33 23/11/07 11:04:24 http://www.mwee.com/204201629 http://www.spinner.de http://www.spinner.de http://www.mwee.com
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