RF Layout Constraints

Proper layout between the RF input pad (Pin 51) on the OEM7500 module and RF input connector on the customer’s interface board is critical for best overall system performance.

• The RF interface (Pin 51) on the OEM7500 module has been optimized to 50 Ω, therefore the interface to Pin 51 (traces into the pin and the entry into the pin pad) must be designed to 50 Ω to ensure proper signal integrity. The RF trace routing on the interface board must be kept away from any digital signals (NovAtel recommends 2 to 4 mm between RF trace and digital trace), such as clock traces or vias that may inject noise into the RF signal.

• As shown in the RF traces on the interface board, the component (L302) which is on the bottom side of the PCB for the antenna power coupling should be placed as close as possible to Pad 51 on OEM7500 module. Vias should be used to connect the top side ground fill to the ground plane on an inner layer of the PCB. The copper pour on the outer layer is important for the RF trace on the interface board as it allows better noise rejection.

RF Interface Circuit Bill of Materials

Reference Designator	Description	Manufacturer	Part Number
C303	CAP CER 10UF 10V 20% X5R 0402	Samsung	CL05A106MP5NUNC
FB301	BEAD FERRITE ILHB 250 OHM 3A SMD	VISHAY-DALE	ILHB0805ER251V
J301	CONN MMCX STRAIGHT PCB RECEPT W/STANDOFF	JOHNSON COMPONENTS	135-3701-201
L301	INDUCTOR CHIP 100nH 5% 0603CS	COILCRAFT INC	0603CS-R10XJLW