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3. Functional Description

3.3.2. 2.4 GHz Receiver

The 2.4 GHz receiver down-converts the RF signals to quadrature baseband signals and

converts them to the digital domain with 2 high resolution high speed ADCs. To adapt to

varying signal channel conditions, RF filters, automatic gain control (AGC), DC offset

cancelation circuits and baseband filters are integrated within ESP8266EX.

3.3.3. 2.4 GHz Transmitter

The 2.4 GHz transmitter up-converts the quadrature baseband signals to 2.4 GHz, and

drives the antenna with a high-power CMOS power amplifier. The function of digital

calibration further improves the linearity of the power amplifier, enabling a state of art

performance of delivering +19.5 dBm average TX power for 802.11b transmission and +18

dBm for 802.11n (MSC0) transmission.

Additional calibrations are integrated to offset any imperfections of the radio, such as:

•

Carrier leakage

•

I/Q phase matching

•

Baseband nonlinearities

These built-in calibration functions reduce the product test time and make the test

equipment unnecessary.

3.3.4. Clock Generator

The clock generator generates quadrature 2.4 GHz clock signals for the receiver and

transmitter. All components of the clock generator are integrated on the chip, including all

inductors, varactors, loop filters, linear voltage regulators and dividers.

The clock generator has built-in calibration and self test circuits. Quadrature clock phases

and phase noise are optimized on-chip with patented calibration algorithms to ensure the

best performance of the receiver and transmitter.

3.4. Wi-Fi

ESP8266EX implements TCP/IP and full 802.11 b/g/n WLAN MAC protocol. It supports

Basic Service Set (BSS) STA and SoftAP operations under the Distributed Control Function

(DCF). Power management is handled with minimum host interaction to minimize active-

duty period.

3.4.1. Wi-Fi Radio and Baseband

The ESP8266EX Wi-Fi Radio and Baseband support the following features:

•

802.11b and 802.11g

•

802.11n MCS0-7 in 20 MHz bandwidth

•

802.11n 0.4 μs guard-interval

•

up to 72.2 Mbps of data rate

Espressif

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