Data Sheet
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Espressif Systems
ESP8266 Datasheet
Figure 3 Illustration of Power Management
6. Clock Management
6.1. High Frequency Clock
The high frequency clock on ESP8266EX is used to drive both transmit and receive mixers. This clock
is generated from the internal crystal oscillator and an external crystal. The crystal frequency can
range from 26MHz to 52MHz.
While internal calibration of the crystal oscillator ensures that a wide range of crystals can be used, in
general, the quality of the crystal is still a factor to consider, to have reasonable phase noise that is
required for good performance. When the crystal selected is sub-optimal due to large frequency
drifts or poor Q-factor, the maximum throughput and sensitivity of the WiFi system is degraded.
Please refer to the application notes on how the frequency offset can be measured.
Espressif Systems / August 1, 2015
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