Use Instructions

L710HG Hardware Design
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5 Design guideline
This chapter provides a general design of the products instruction, the user can refer to design
guidance for design, make products to achieve better performance
.
5.1 General design rules and requirements
Users in the design of this product is peripheral circuit, the first to ensure the external power supply
circuit can provide enough power supply capacity, And the requirements for high speed signal lines
USB control 90 ohm + / - 10% difference impedance. For general signal interface, require the user to
us in strict accordance with the requirements of design, in line with the interface signal level matching,
in case the level of damage to the module. This product its own radio frequency index is good,
customers need to design in accordance with the requirements the mainboard side antenna circuit and
corresponding impedance control, otherwise it will affect the whole RF index
.
5.2 Reference circuit
Overall reference circuit design please refer《L710HG reference design》.
5.3 RF part design guideline
5.3.1 Early antenna design considerations
 Pre-project evaluation
The selection of the antenna position must first ensure that the antenna and the base station are kept in
the horizontal direction, this produces the highest efficiency; Secondly, try to avoid placing the switch
in the power supply or data line, chip and other devices or chips that produce electromagnetic
interference. At the same time, the position of the hand can be avoided, so as to prevent the human
body to produce attenuation; But also to reduce the radiation and the structure of the realization of the
need to take into account. So, At the beginning of the design need to structure, ID, circuit, antenna
engineers together to evaluate the layout.
 Antenna matching circuit
If the module's radio frequency port and the antenna interface need to be transferred, the main board
circuit design, The design of microstrip line or strip line between the module RF test base and the
antenna interface between the microstrip line or the strip line by characteristic impedance 50 ohm, at
the same time, reserved double L type matching circuit; If the antenna's RF connector can be directly
stuck in the module's RF test base, can save the module of the RF port and the antenna interface