Data Sheet

Datasheet

iM980A

iM980A_Datasheet_mcf88.docx, v1.2 Page 16

7.2 PCB Design Recommendation

The Top Layer of the carrier board should be kept free of Tracks and Vias under

the iM980A because there are some test pads on the bottom side of the

module which are not covered by solder resist.

All GND pads of the module should be connected via low impedance path to

GND.

The iM980A's RF interface is already matched to 50  By using an adequate

50  antenna, no additional matching components are required

. For an ideal

signal transmission between the modules RF pad and the antenna, the

transmission line should be as short as possible and represent an impedance of

50 .

This impedance depends on frequency and PCB structure. It is recommended

to use a grounded coplanar waveguide (CPWG) structure, to reduce effects

of electromagnetic fields. The impedance of transmission line for grounded

CPWG is basically affected by height H and material of the substrate, gap G

between transmission line and ground on the top layer, as well as width W and

thickness T of the transmission lines (Figure 7-2).

GND

GND GNDRF

GG W

Figure 7-2: Structure of a grounded CPWG

In other case a special matching network is required

Note:

Disregarding this recommendation can affect the RF

performance respective RF output power, sensitivity, and

unwanted emissions.