AN1949 STMicroelectronics, AN1949 Datasheet - Page 5

• Manufacturer Part Number: AN1949
• Description: RFID Reader using STMicroelectronics PSD MCU and CRX14 Coupler to Implement a China National ID Card Reader
• Manufacturer: STMicroelectronics

AN1949 - APPLICATION NOTE
Debugging Procedure
Some debugging might be needed, to make the boasted antenna circuit work properly.
Test the Output of the CRX14. The signal on the RF
pin should be 10% ASK modulated on a carry
OUT
frequency of 13.56MHz.
Test the Output of the Class E Amplifier. The signal after L7 (test point 2, on the schematic diagram)
should be the amplified signal of RF
, as shown in
Figure
3.. If there is no signal, you should check the
OUT
transistor and the passive components around it.
Optimize the Antenna. The Input Impedance of the antenna (Z
), and its matching circuit, should match
a
the output impedance of the Class E amplifier, see
Figure
4.. Because of slight differences among PCB
materials, or other problems, the features of the antenna may vary, such as the inductance (L
) of the an-
a
tenna, and the resistance (R
). It is necessary to make some adjustment of the antenna matching circuit
p
to achieve high performance.
Figure 3. Testing the Output of Class E Amplifier
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