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AS3991 UHF RFID Reader IC

ams' UHF RFID reader chip with built-in programming options

ams - AS3991 UHF RFID Reader ICams' AS3991 UHF reader chip is an integrated analog front end and data framing system for a 900MHz RFID reader system. Built-in programming options make it suitable for a wide range of applications in UHF RFID systems. Designed to simplify the design and implementation of an EPC Class1 Gen2 reader, this IC only requires a standard 8-bit microcontroller and a minimum number of other components.

The AS3991 comprises the EPC Class1 Gen 2 protocol (ISO 18000-6c) with digital high-speed logic up to the framing level and supports the ISO 18000-6a and ISO 18000-6b protocol with direct data mode. Either the interface to the microcontroller can be a 4-pin serial data interface (SDI) or an 8-bit parallel interface if high data rates are necessary. Frame management is accomplished using a 12-byte FIFO in order to decrease processor workload, ensure a smooth data stream, and correct protocol handling. All low level transmission codecs and CRC generation is done internally.

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  • Applications
  • Diagram
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  • Fully compliant with ISO 18000 6a, 6b, 6c and EPC Class1 Gen2 protocol using external MCU
  • EPC Class1 Gen2 framing support using low cost 8-bit microcontroller
  • Direct data mode in the frequency range of 860 to 960MHz enables propriety protocol support
  • Internal power amplifier with level controlled 20dBm for short range applications (only available on the AS3991)
  • Modulator using ASK or PR-ASK modulation
  • Adjustable ASK modulation index
  • Automatic selection between I and Q signal ensuring no “communication holes”
  • Built-in reception low-pass and high-pass filters have selectable corner frequenciesRoHS Compliant
  • On chip VCO and PLL covering complete RFID frequency range and frequency hopping support
  • Selectable receiver gain with AGC
  • Supported link frequencies from 40 up to 640kHz


  • RFID label printers
  • Add-on module for handheld computers, PDAs
  • Point of sales equipment
  • UHF RFID reader systems
  • Hand-held UHF RFID readers
  • Toll systems
  • Mobile phones
  • Shelf readers


AS3991 Diagram

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Digi-Key P/N ams P/N Description Datasheet
 Available in Tape & Reel (TR-ND), Cut Tape (CT-ND), and custom Digi-Reel® (DKR-ND)