How does the nrf24l01 do during tx setting time?

[jane_song]

Hi all,
   We use a kind of widely used nrf24l01 module in our product developement.It use the nodic's reference design of nrf24l01 with an external pa/lna.TXEN and RXEN of the external PA/LNA is respectively connect to the VDD_PA and CE of nrf24l01.I brouse some related issues about VDD_PA in Q&A of dev zone. When the nrf24l01 is in 130us tx setting time, the VDD_PA is low in early 80us and then is high.In other word, the VDD_PA is high 50us before the actual tx mode(begin to send on air data).So how does the nrf24l01 do during tx setting time?More detail about the 80us + 50us?I once thounght it was idle during tx setting time.However recently I thought it was still sending something(like 0 or 1) from my recent test.

[ovrebekk]

Hi

Enabling the PA will affect the PLL frequency temporarily, and it is necessary to run the PA and the PLL together for a short time before sending the packet to make sure that the PLL is stable once you start packet transmission. 

The PA will run at limited output power during this stage, but there might be some output on the antenna, yes. 

Essentially this period is essential to ensure that the frequency and level of the radio signal is stable once the packet transmission starts. 

Best regards
Torbjørn