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Problem to get +16dB as Output Power from SPIRIT1

Question asked by tiagoSantos on Jul 28, 2016
Latest reply on Oct 19, 2016 by tiagoSantos

Hi, I am a beginner with RF and SPIRIT1. I’ve been working with SPIRTI1 for more than a month by now and I am having some problems regarding de cofiguration of the output power of this device.

I am not able to get +16dBm as output power from the CI I am using. I used a spectrum analyser to measure the frequency and output power of the SPIRIT1 and as result I got -1.95 dBm as output power, the parameters refering to frequency are correct, but the output power is much lower of what I was expecting.

I would like to ask for some ideas of what could be wrong with my design (hardware and/or firmware).

The SPIRIT1 is working at 172MHz, GFSK with BT = 1, basic packet, 100kbps data rate, output power = +16dBm (at least, it should be).

I am able to transmit and receive basic packets up to a distance of 50m without any erros, using CSMA or not, with CRC filtering enable.

Regarding the output power, do I only need to set those two registers? POWER[8] (0x10) and POWER[0] (0x18)? I’ve written them as 0x01 and 0x07, respectively.

I would like to receive some suggestions of what I should do to verify possible problems which could be the cause of this deviation in the output power.

Regarding the hardware setup for the device, I am using the circuit diagram for tx boost mode, figure3 of the datasheet. The value of the components I go from the table 3 BOM of the datasheet.

What I am doing now is verifying if the soldering and the components are correctly placed, but I do not know what more tests and verifications I could do in order to discover the problem with the output power.

Any suggestions are very much appreciated.