Melexis introduces new 300-to-930-MHz RF Receiver Family

Ieper - Belgium – 5 of November 2007 – The Melexis MLX71120 and MLX71121 are two new members of a highly integrated RF receiver family. Both automotive qualified ICs with dual RF inputs 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 new MLX71120/MLX71121 RF receiver ICs are tailored for low-power and low-cost fixed frequency applications. They can address the European 863 - 870MHz SRD bands or the ISM bands at 902 – 928MHz in North America. At the same time the new receiver chips are applicable for the lower frequency bands at 315MHz (e.g. in the US) or at 433MHz (e.g. in Europe and China). Manufacturers of world-wide 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.

One of the outstanding features of the two new receivers MLX71120 and MLX71121 is their dual RF input. This allows the user to very 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 433MHz and a second at 868MHz.

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.

The small 32 lead QFN package with a footprint of 5mm x 5mm and the fact that no bulky external ceramic filter and discriminator components are necessary to make the MLX71120/71121 the optimum choice for systems requirint the smallest PCB footprint and the lowest circuit cost.

The MLX71120/71121 operates over a wide supply voltage range from 2.1 to 5.5V with a typical current consumption of 6.5 to 11mA. In standby mode the current draw is below 50nA. The receiver input sensitivity is as low as -113dBm for ASK and -112dBm (MLX71120) and -107dBm (MLX71121) for FSK signals, respectively.

The MLX71120/71120 receivers combine flexibility with high levels of circuit complexity. They dramatically reduce system costs thanks to the internal IF filter and FM/FSK demodulator. The receivers’ AFC feature can tolerate frequency uncertainties of the input signal.

Dr. Andreas Laute, Manager of Melexis’ Business Unit Wireless Communication, states: “With the introduction of these new devices of our highly integrated RF receiver family, we provide tools for our customers to ease the development of state-of-the-art receiver systems. The MLX71120/71121 with their antenna diversity feature will be a revolution in the low-cost RF receiver segment.”

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.