Impedance Matching - Espressif ESP8266 Matching Manual

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3.
5
The impedance of ESP8266 PA output end is 39+j6 Ω, so the matched impedance is 39-j6
Ω (from antenna to the chip).
For EMC test, the π-type impedance matching circuit of external antenna should be as
shown in Figure 3-1.
�� Notes:
C1 must be a 2.4 pF capacitor for filtering harmonics twice.
•
L1, C2, along with C1 perform 39-j6 Ω impedance matching for antenna.
•
L1 and C2 can be inductors or capacitors as required.
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Espressif

Impedance Matching

4
Antenna
C1
2.4pF
!
Figure 3-1. Antenna Impedance Matching
L1 NC
GND GND
! /! 4 5
3. Impedance Matching
3
C2
NC
2016.06
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