Analog Devices ADF7021-N Product Info

• Low power, narrow-band transceiver
• Frequency bands using dual VCO
  80 MHz to 650 MHz
  842 MHz to 916 MHz
• Programmable IF filter bandwidths of
  9 kHz, 13.5 kHz, and 18.5 kHz
• Modulation schemes: 2FSK, 3FSK, 4FSK, MSK
• Spectral shaping: Gaussian and raised cosine filtering
• Fully automatic frequency control loop (AFC)
• On-chip, 7-bit ADC and temperature sensor
• On-chip VCO and fractional-N PLL
• Data rates supported: 0.05 kbps to 24 kbps
• 2.3 V to 3.6 V power supply
• Programmable output power
  −16 dBm to +13 dBm in 63 steps
• Automatic power amplifier (PA) ramp control
• Receiver sensitivity
  −130 dBm at 100 bps, 2FSK
  −122 dBm at 1 kbps, 2FSK
• Patent pending, on-chip image rejection calibration
• Digital received signal strength indication (RSSI)
• Integrated Tx/Rx switch
• 0.1 μA leakage current in power-down mode

The ADF7021-N is a high performance, low power, narrow-band transceiver based on the ADF7021. The ADF7021-N has IF filter bandwidths of 9 kHz, 13.5 kHz, and 18.5 kHz, making it ideally suited to worldwide narrowband standards and particularly those that stipulate 12.5 kHz channel separation.

It is designed to operate in the narrow-band, license-free ISM bands and in the licensed bands with frequency ranges of 80 MHz to 650 MHz and 842 MHz to 916 MHz. The part has both Gaussian and raised cosine transmit data filtering options to improve spectral efficiency for narrow-band applications. It is suitable for circuit applications targeted at the Japanese ARIB STD-T67, the European ETSI EN 300 220, the Korean short range device regulations, the Chinese short range device regulations, and the North American FCC Part 15, Part 90, and Part 95 regulatory standards. A complete transceiver can be built using a small number of external discrete components, making the ADF7021-N very suitable for price-sensitive and area-sensitive applications.

The range of on-chip FSK modulation and data filtering options allows users greater flexibility in their choice of modulation schemes while meeting the tight spectral efficiency requirements. The ADF7021-N also supports protocols that dynamically switch among 2FSK, 3FSK, and 4FSK to maximize communica-tion range and data throughput.

The transmit section contains two voltage controlled oscillators (VCOs) and a low noise fractional-N PLL with an output resolution of <1 ppm. The ADF7021-N has a VCO using an internal LC tank (421 MHz to 458 MHz, 842 MHz to 916 MHz) and a VCO using an external inductor as part of its tank circuit (80 MHz to 650 MHz). The dual VCO design allows dual-band operation where the user can transmit and/or receive at any frequency supported by the internal inductor VCO and can also transmit and/or receive at a particular frequency band supported by the e