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SX1262 Tx power less than -10 dBm

Semtech Transceivers SX126x family
#1

Hello everyone,

Recently I was doing some tests and found out that a device with SX1262 transcevier that is supposed to transmit at -10 dBm actually transmits at nearly +20 dBm. I did a little bit of measuring and found out that my code works perfectly fine between +22 and -9 dBm, however, for -10 dBm and less, it “wraps around” to +22 dBm.

I tried a couple different values of parameters for the setPaConfig command (my code uses paDutyCycle = 0x04, hpMax = 0x07 and deviceSel = 0x00 by default), but I was not able to get SX1262 to output signal level below -9 dBm.

According to the datasheet, it should be possible to transmit as low as -17 dBm. So, my question is: what are the recommended settings for operation below -9 dBm? Thanks!

#2

Hi @gromes.jan,

A SX1262 is capable of transmitting data between -9dBm and +22dBm. Only the SX1261 can transmit down to -17dBm.

1 Like
#3

Ah, OK, my bad. Thanks!

Although it’s not entirely clear in the datasheet in my opinion. Nowhere is it explicitly stated that SX1262 can only go down to -9 dBm. There are some graphs that show this, and also the sentence “- 9 (0xF7) to +22 (0x16) dBm by step of 1 dB if high power PA is selected”, but it’s up to the reader to jump to the conclusion that “high power PA” = “SX1262 device”.

By the way, is there some document that would go a bit more in depth on the PA configuration parameters such as hpMax and paDutyCycle? The description in datasheet does list some specific recommended values, but doesn’t go into much detail to explain how the parameters influence the output signal level.

1 Like
#4

Hi @gromes.jan

Please refer to Semtech Application Note AN1200.54 for information regarding adaptive matching techniques.

#5

I’ll take a look, thanks for the pointer.