AS3993-DK FERMI ams, AS3993-DK FERMI Datasheet - Page 16

• Manufacturer Part Number: AS3993-DK FERMI
• Description: RFID Transponder Tools AS3993 Demo Board Fermi
• Manufacturer: ams

Specifications of AS3993-DK FERMI

• Rohs: yes
• Product: RFID Readers
• Description/function: Demonstration Reader
• Frequency: 20 MHz
• Interface Type: SPI, USB
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Operating Supply Voltage: 5 V
• Tool Is For Evaluation Of: AS3993
• For Use With: AS3993 UHF RFID Reader IC

AS3993 – AN13 – Received Signal Strength Indicator (RSSI)
Directional Coupler and RX Balun Section:
Figure 12 - Schematic Directional Coupler
The directional coupler also includes a low pass filter which attenuates the higher order
harmonics of the carrier signal. The directional coupler is needed in order to prevent the TX
signal leaking into the receiver. The used coupler is a trade-off between cost and directivity. The
antenna connector is a U.FL connector which is compatible with a microcoaxial connectors.
Since the directional coupler is a 10 dB coupler only 10 dB of the incoming tag signal is fed to
the RX Balun which converts the 50 ohm single ended impedance back to 100 ohm differential
need for the differential RX ports of the reader IC.
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Revision 2.0 / 6/22/12
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