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Zigbee ref design eliminates antenna, RF balun

Posted: 30 Mar 2007 ?? ?Print Version ?Bookmark and Share

Keywords:Zigbee? IEEE 802.15.4? Zigbee reference design?

Jennic introduced a Zigbee- and IEEE 802.15.4-node reference design for its JN5139 wireless MCU, which is said to reduce the BOM cost of modules for wireless sensor networks to under $5. This includes the cost of the JN5139 wireless microcontroller, a PCB antenna design, and all other ancillary components.

To achieve the sub-$5 price point the RF circuit, antenna and RF balun components have been eliminated by using a balanced antenna printed on the circuit board, requiring no additional components to match to the chip's 200-ohm resistive differential RF interface. By designing the antenna to interface directly to the chip, the balun losses are removed, giving a 1.5dB improvement in receive sensitivity and transmit power. Also, the design of the antenna has higher gain (around 4dBi) than the ceramic antenna (approximately 1.5dBi) it replaces.

For the PCB, by providing a two-layer reference design measuring 49-by-25mm, including the antenna area, the cost of the entire application board can be kept to a minimum. This is important in many low-cost products with large application boards, such as lighting or remote control, where the design cannot sustain the cost of a four-layer board, as used in many conventional RF reference designs.

The JN5139 is available and has been tested for spurious emissions and meets the regulatory requirements of both the United States and Europe.

- Emily Gleason

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