I have a customer board using CC110L, 433M, 250kbps. The sensitivity is about 6 dB worse than the CC110L evaluation board (EVB). Here is how I do the test:
1. The register setting is from Smart RF studio
2. Transmit packets using another board with the same settings, except the PA_TABLE, which is set to 0 in the Tx side, and the output power is about -65dBm. I
didn't use max power (10 dBm) in the Tx side, because I don't have a shielding box. If I use 10 dBm, the power transmitted over the air will be larger than through the
cable.
3. Connect Rx side to the Tx side, with an adjustable attenuator between them.
4. In Rx side, packets are received and PER is calculated.
5. For EVB, the same Tx source and attenuator is used, but PER is calculated by Smart RF studio (packet Rx).
6. The result shows the sensitivity is about -94 dBm on EVB, vs -88 dBm on my own board.
7. I also noticed that the RSSI reading is about 6 dB lower than the actual input on my own board. And they are nearly the same on EVB. For example, when the attenuator
is 0 dB, the RSSI reading is about -72 dBm on my own board, and is -66 dBm on EVB. When it reaches sensitivity limit, the RSSI reading on my own board is also about -94 dBm when the
actual input power is -88 dBm.
8. The max power is about 10.5 dBm and should be good (PA_TABLE 0x30).
The SCH is exactly the same as in the CC110L datasheet (6.2 of SWRS109C), and all component values are as listed in the document, except C126, which is 0 ohm on my own board.
Also I attached my PCB.
Could you please take a look at the cause of the issue, and how can I investigate this issue futher?
Thanksbottom.pdftop.pdf
