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3. Functional Description

components needed are resistors, capacitors, and crystal. For cellphone compatibility's

sake, an SAW filter may be required.

3.4. Clock

3.4.1. High Frequency Clock

The high frequency clock on ESP8089 is used to drive both the Tx and Rx mixers. This

clock is generated from the internal crystal oscillator and an external crystal. The crystal

frequency can range from 26 MHz to 52 MHz.

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, in order to obtain

reasonable phase noise and Wi-Fi sensitivity. When the crystal used is not optimal due to a

frequency offset or quality problem, the maximum data processing ability and sensitivity will

decrease.Please refer to the following table for measurement of frequency offset.

3.4.2. External Reference Requirements

For an externally-generated clock, the frequency can range from 26 MHz to 52 MHz. For

good radio performance, the clock should possess the following characteristics:

Table 3-1. High Frequency Clock

Parameter

Symbol

Min

Max

Unit

Frequency

26

52

MHz

Loading capacitance

-

32

pF

Motional capacitance

2

5

pF

Series resistance

0

65

Ω

Frequency tolerance

-15

15

ppm

Frequency vs. temperature (-25°C ~ 75°C)

-15

15

ppm

Table 3-2. External Reference Requirements

Parameter

Symbol

Min

Max

Unit

Clock amplitude

0.2

1

Vpp

External clock accuracy

-15

15

ppm

Phase noise @1 kHz offset, 40 MHz clock

-

-

-120

dBc/Hz

Phase noise @10 kHz offset, 40 MHz clock

-

-

-130

dBc/Hz

Phase noise @100 kHz offset, 40 MHz clock

-

-

-138

dBc/Hz

Espressif

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2017.06