Help SIM5320 Breakout Board construction for Raspberry Pi model B

Question

I need a breakout board based on SIM5320 for experimenting web server http requests. I've found the board shown above in adafruit library and thought of using it as reference and slim it down to the requirements by removing unwanted circuitry.As marked in the pic, all the circuits marked with cross are not needed. And the component to which the arrow mark is pointing is the one I need to know how to create one similar to it in Altium or Eagle cad. I see it says GPS BIAS with 33nH inductor and not sure what those half rounded pads with pin nos connected to or the component type used.

Also for this board I'll be using 9V external voltage source along with LDO circuit as mentioned in the SIM5320 Datasheet.I've calculated the required resistances to be used to get the desired LDO output voltage. Also I will be be using all 3 protocols (UART, SPI, I2C) and for these I will be putting separated headers so that I can use the desired ones when needed.I hope that should be enough to RPi to take care of SIM5320 . Need some one to check my approach and let me know If there are any other changes to be done in the circuitry.

Answer 1

That component is a solder jumper to enable optional antenna power. Meaning, it is a special footprint on your PCB that can be easily bridged with solder in order to make a connection. Alternatively, you can remove the solder the break the connection. Solder jumpers are commonly used for board configuration when they are a connection that will be rarely changed.

I haven't used Eagle in a while, but IIRC Sparkfun distributes an Eagle library which includes the above symbol and a footprint or two for solder jumpers. If you don't want to bother, you could also use a resistor in the schematic (0Ω, DNP) and set it as an 0402 or 0603 footprint. Then a zero ohm resistor or small bit of wire can be used. Making your own footprint is also an option.

See page 48 of the datasheet. It shows an application circuit for both an active and passive antenna. If you know you are only going to be using a passive antenna, you can eliminate the circuit beyond the solder jumper (all you need is the antenna connector and a tuning network, which the Adafruit schematic doesn't seem to include).

Regarding your other circuitry: if you aren't using the LiPo battery stuff, and no microphone, then removing those blocks is fine. As long as all your logic I/O is 3V3, then removing the level shifting is also fine.