QUESTION

Question

Technical support:

Nice to meet you. I am Defond company engineer. I am responsible for develop GNSS platform in IOT product. I would like to use M20057-1 GNSS module. SIM7070 IC GNSS pin will connect to  M20057-1 RFO. There are two external matching components for AT1 and AT1. How to determine these external mattching two components value? 

Another question, does it need to make a matching circuit in RFO pin?

Thanks in advance.

Answer 1

Hello Defond,

AT1 should start with a zero ohm resistor. AT2 should start with a 1.8nH inductor. In order to start tuning the antenna a coax cable should be placed at the GNSS pin at the SIM7070 module. The antenna should be placed in the plastic housing before adjusting the matching components on AT1 and AT2. The tuning should be optimized until the band edges meet -10dB return loss (2:1 VSWR).

Also, on the trace from RFO to the GNSS pin there should be a series 22pF capacitor and a 47nH on the VCC supply to the M20057. These components should be in place when you start tuning the antenna.

Best regards,

Geoff S.