Maxim Integrated Products has launched a very sensitive VHF/UHF PLL-based FSK receiver. The MAX7042 achieves better than -110 dBm of FSK sensitivity, claimed Maxim. It can be used where an external LNA is currently required to achieve such sensitivity. The device's performance makes the external LNA superfluous, reducing overall system cost. The MAX7042 also includes an on-chip, 44 dB (typ) image rejection mixer that eliminates the need for SAW filters in many applications. The part operates off 3.3 V or 5 V supplies and down to 2.4 V. Housed in a small, 5 mm × 5 mm, 32-pin thin QFN package, this receiver is suitable for low-cost, high-volume applications where range is critical. Typical applications are car alarm key fobs, RF modules, security products, remote controls, and remote sensors operating at 308 MHz, 315 MHz, 418 MHz and 433.92 MHz.

All the active components required in a superheterodyne receiver are included in the MAX7042: a low-noise amplifier (LNA), an image rejection (IR) mixer, a fully integrated phase-locked-loop (PLL), a local oscillator (LO), a 10.7 MHz IF limiting amplifier with receive-signal-strength indicator (RSSI), a low-noise FM demodulator, and a 3 V regulator. A differential peak detecting data demodulator is also included for analog baseband, data-recovery circuitry.

The MAX7042 draws approximately 20 nA in shutdown mode and only 6.4 mA in receive mode. Depending on the components selected, the MAX7042 can receive up to 66 kbps data rates (NRZ) and transitions from shutdown to valid data out in less than 250 microseconds. In power-cycled applications, this quick transition minimizes the time that the system needs to be in receive mode. It operates over the automotive temperature range (-40 °C to +125 °C).

For more information, visit www.maxim-ic.com