COMMUNICATION SOLUTIONS

Transceiver Provides Outstanding ISM Performance

The ADF7021 from Analog Devices is a high performance narrowband ISM transceiver IC, designed for use in a wide range of frequency bands from 80MHz to 940MHz. With best-in-class sensitivity and low transmit-mode power consumption, the device can reduce component count in automated meter reading, wireless home automation and multiple wireless connectivity applications.


Functional Diagram

This highly integrated 2FSK/3FSK/4FSK transceiver is suitable for circuit applications targeted at European ETSI-EN 300-220, the Japanese ARIB STD-T67, the Chinese Short Range Device regulations and the North American FCC Part 15, Part 90 and Part 95 regulatory standards. It includes an on-chip T/R switch, VCO tank, RF/IF filters and fully automatic AFC and AGC features that reduce external component count and make the device highly suitable for price sensitive and space constrained applications.

The ADF7021 offers both Gaussian and raised cosine data filtering options to improve spectral efficiency for narrow-band applications. Its receiver sensitivity of -123dBm at 1kbps combines with superior interference blocking to make it well suited for high reliability and maximum range applications such as wireless AMR (Automatic Meter Reading), wireless home automation, industrial control and monitoring and remote security.

The transceiver RF frequency, channel spacing and modulation are programmable via a simple three-wire interface. The device operates with a power supply range of 2.3V to 3.6V and can be powered down when not in use.

The transmit section contains a VCO working at twice the fundamental frequency and a low noise fractional-N PLL with output resolution better than 1ppm. This frequency-agile PLL allows the ADF7021 to be used in Frequency Hopping Spread Spectrum (FHSS) systems. Output power is programmable in 63 steps from −16dBm to +13dBm and has an automatic power ramp control.

The receiver employs a low (100kHz) IF architecture to reduce power consumption and the external component count while avoiding interference problems at low frequencies. The IF filter has programmable bandwidths of 12.5kHz, 18.75kHz and 25kHz. Receiver linearity, sensitivity and IF bandwidth are all programmable, allowing the user to trade off receiver sensitivity and selectivity against current consumption. A patent pending Automatic Frequency Control (AFC) loop, with programmable pull-in range, allows the PLL to track out the frequency error in the incoming signal.

Features

• Highly integrated narrowband ISM transceiver
• 2FSK/3FSK/4FSK modulation
• Wide range of frequencies
  • 80MHz to 650MHz
  • 862MHz to 950MHz
• Sensitivity up to -123dBm
• Programmable output power: -16dBm to +13dBm in 63 steps
• Gaussian and raised cosine filtering
• Data rates 0.05kbps to 32.8kbps
• 2.3V to 3.6V power supply
• Automatic PA ramp control
• Fully Automatic Frequency Control loop (AFC)
• Digital Received Signal Strength Indication (RSSI)
• Integrated Tx/Rx switch
• 0.1µA leakage current in power-down mode
• On-chip, 7-bit ADC and temperature sensor
• Parameters programmable via three-wire interface

Applications

• Low cost wireless data transfer
• Remote control/security systems
• Wireless metering
• Private Mobile Radio
• Wireless Medical Telemetry Service (WMTS)
• Keyless entry
• Home automation
• Process and building control
• Pagers

For further information, including the ADF7021 Datasheet, please click here