A S 3 9 9 0 / A S 3 9 9 1
U H F R F I D S i n g l e C h i p R e a d e r E P C C l a s s 1 G e n 2 C o m pa t i b l e
1 General Description
The AS3990/AS3991 UHF reader chip is an integrated
analog front end and protocol handling system for a
ISO18000-6C 900MHz RFID reader system.
Equipped with built-in programming options, the device
is suitable for a wide range of applications in UHF RFID
systems.
The reader configuration is achieved by selecting the
desired protocol in control registers. Direct access to all
control registers also allows fine tuning of different
reader parameters, if needed.
Parallel or serial interface can be selected for
communication between the host system (MCU) and the
reader IC. When hardware coders and decoders are
used, transmission and receive data is transferred via.
24 bytes FIFO register.
In case of direct transmission or reception, coders and
decoders are bypassed and the host system has to
service the analog front end in real time.
The transmitter generates 20dBm output power into 50Ω
load and is capable of ASK or PR-ASK modulation. The
integrated supply voltage regulators ensure supply
rejection of the complete reader system.
The transmission system comprises low level data
coding. Automatic generation of FrameSync, Preamble,
and CRC is supported.
The receiver system allows AM and PM demodulation.
The receiver also comprises automatic gain control
option (patent pending) and selectable gain and signal
bandwidth to cover a range of input link frequency and
bit rate options.
The signal strength of AM and PM modulation is
measured and can be accessed in RSSI register.
The receiver output is selectable between digitized sub-
carrier signal and any of integrated sub-carrier
decoders. Selected decoders deliver bit stream and data
clock as outputs.
The receiver system also comprises framing system.
This system performs the CRC check and organizes the
data in bytes. Framed data is accessible to the host
system through a 24 byte FIFO register.
To support external MCU and other circuitry a 3.3V
regulated supply and clock outputs are available. The
regulated supply has 20mA current capability.
The AS3990/AS3991 is available in a 64 pin QFN (9mm
x 9mm), ensuring the smallest possible footprint.
www.austriamicrosystems.com
Revision 3.0
2 Key Features
3 Applications
The device is an ideal solution for UHF RFID reader
systems and hand-held UHF RFID readers.
ISO18000-6C (EPC Gen2) full protocol support
ISO18000-6A,B compatibility in direct mode
Integrated low level transmission coding
Integrated low level decoders
Integrated data framing
Integrated CRC checking
Parallel 8-bit or serial 4 pin SPI interface to MCU
using 24 bytes FIFO
Voltage range for communication to MCU between
1.8V and 5.5V
Selectable clock output for MCU
Integrated supply voltage regulator (20mA), which
can be used to supply MCU and other external
circuitry
Integrated supply voltage regulator for the RF output
stage, providing rejection to supply noise
Internal power amplifier (20dBm) for short range
applications
Modulator using ASK or PR-ASK modulation
Adjustable ASK modulation index
AM & PM demodulation ensuring no
“communication holes” with automatic I/Q selection
Built in reception low-pass and high-pass filters
having selectable corner frequencies
Selectable reception gain
Reception automatic gain control
AD converter for measuring TX power using
external RF power detector
DA converter for controlling external power amplifier
Frequency hopping support
On-board VCO and PLL covering complete RFID
frequency range 840MHz to 960MHz
Oscillator using 20MHz crystal
Power down, standby and active mode
Can be powered by USB with no need for step
conversion
P r o d u c t B r i e f
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