I am presently looking to use HL7800 in one of small form factor boards. Hence, space is a constraint and I am aiming to place components on both sides of PCB. Here are a few of my queries:
Can we place components below the module ( in Bottom Layer ) except antenna and SIM section? Components include micro-controller and power supply section.
Can we route wires and place vias under the module ( in inner layers and bottom layer ) except antenna and sim section?
Any specific board stack-up recommended ? How many layers?
Yes you can mount components on the other side of the board to the HL78, this includes the SIM, the shorter the lines for this the better. Obviously the antenna needs to be away from the module.
Yes you can route other signals in lower layers underneath the unit just employ sensible design practices with regards shielding grounding, etc.
Not there is not specific layout recommended or required, designers can make their boards as complicated or simple as they want.