Espressif ESP8266 Matching Guide

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3. Impedance Matching
3. Impedance Matching"
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.
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Figure 3-1. Antenna Impedance Matching
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
Antenna
GND GND
Title
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11Tuesday, May 26, 2015
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11Tuesday, May 26, 2015
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C1
2.4pF
L1 NC
C2
NC
📖 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.
Espressif
! /!4 5
2016.06

Espressif ESP8266 Specifications

General

Digital I/O Pins	17
Analog Input Pins	1
Wi-Fi	802.11 b/g/n
Operating Voltage	3.0V - 3.6V
Clock Speed	80 MHz / 160 MHz
Operating Temperature	-40°C to 125°C
Dimensions	24mm x 14mm
Processor	Tensilica L106 32-bit micro controller