Electronic Design

Low-Cost Wireless Transceiver Fits Short-Range Point-To-Point Applications

ZigBee, Bluetooth, WirelessUSB, and the new ultra-wideband devices are formidable technologies, but they're overkill for many wireless needs. For simpler point-to-point wireless applications, designers can turn to the AMIS-52100 wireless transceiver. Developed by AMI Semiconductor, it targets short-range data links, wireless monitors, remote sensors, and other uses in the industrial and automotive sectors. Medical sensors, especially implantable sensors, represent a particularly interesting application.

The AMIS-52100 has a total operating range of 300 to 768 MHz, with its sweetspot between 402 and 405 MHz. This range happens to be the Food and Drug Administration's Medical Implantable Communications System (MICS) band, which was allocated in 1999 as an alternative to magnetic coupling wireless techniques also used in implantable devices. The chip uses amplitude shift keying (ASK) or on-off keying (OOK) for simplicity. The data rate is 1 to 8 kbits/s using Manchester coding and 1 to 16 kbits/s if the standard NRZ data format is used. The maximum transmitter output power is 12 dBm (15.8 mW) using a 3.6-V supply.

The device incorporates two full independent receivers for diversity reception. The sensitivity is an astounding −117 dBm minimum at 1 kbit/s. The receivers use a very low IF, and the IF filters are fully on-chip. Full clock and data recovery has an auto data-slice threshold level. After demodulation, the binary signal is processed to produce an optimally sampled data bit stream and clock signal that's synchronized with the incoming data, removing jitter and maximizing the data integrity. The recovered clock can be used to sync with an external processor.

The transceiver's patent-pending Quick Start oscillator possesses an extremely fast 15-µs turn-on time. As a result, the on-board receiver can quickly power up to check for the presence of a signal in its patented Sniff Mode. To date, no other oscillator pops on this fast. This feature enables the chip to idle in extreme low-power mode and then wake up according to a programmed timing sequence to look for signals. In many applications, only a very low duty cycle is needed to capture and transmit the desired data.

Besides the serial data in/out, the transceiver has an I2C interface for control by an external embedded microcontroller. The operating dc voltage range is 2.3 to 3.6 V. Transmit current consumption is 25 mA and receive current is 7.5 mA, while standby current is 500 nA. In Sniff mode, it's 75 µA.

The AMIS-52100, which comes in a 20-lead SSOP, costs $1.95 in 50,000-unit quantities. Samples and evaluation kits are available now. The device also can be integrated into ASICs.

AMI Semiconductor
www.amis.com

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