Amplifying nRF24L01P signal

[kwas]

Hi guys,

I am trying to use a TM2001 amplifier (Taiwan Microelectronics, google returns the PDF) to amplify the signal from an nRF24L01P.

The TM2001 seems to accept a 50ohm signal. I use the "application example" on the nordic chip on page 66.

I simply connect the TM2001 RADIO input to the 50 ohm line instead of a chip antenna. Then TM2001 has its own output which goes to an antenna.

I have used TM2001 before with no problems. However now it is giving very strange effects.

There is way too much power consumption from it. If I touch the antenna it affects how much power is drawn. No radio output is observed unless I artificially raise the resistance of the battery supply (by adding a 10 ohm resistor). Is it delusional to think that I can just hook up the TM2001 like I described? The only part of this circuit I don't understand is the inductors/capacitors between ANT1 ANT2 and VDD_PA. Are the inductors causing this problem? Should I just connect ANT1 or ANT2 to the TM2001?

thanks

[kwas]

After trying all possible permutations, it appears as if a 56 ohm resistor is needed between NRF24 output (after the matching network) and before TM2001 radio input. Without this only one TM2001 out of many works properly when duty cycling. Without duty cycle, they all work.

Is this reducing my radio power? What is the reason that this makes it work?

[Andreas]

Hi,

 

This is very strange. It would be interesting to have a look at your schematic and layout files, feel free to create a new private case if you do not want to share the files publicly.

 

Best regards,

Andreas

[kwas]

How can I post files? I have Mentorgraphics PADS SCH and PCB files.

[kwas]

New information

- it's a NRF24L01 not the + version

- even with the 56 ohm resistor, if I touch the bottom of the board (ground) the radio stops (not everything else).

I noticed that the non-+ version needs a 1M R across the crystal, is that just because of the specific crystal that is used in the demo board? I have a crystal I have been using with a series R not parallel and it seems it won't work without series R and with a parallel R. I haven't tried using both yet but I will.

[kwas]

Adding R1 (1M across crystal leads) does not change anything. Touching ground wipes NRF registers. Only when I reset the MCU and it reinitializes, does it start transmitting again. Same issue with not using 56 OHM resistor, it sends one packet and then dies. What could be wrong? Do you have an email I can send files to?