Hi all,
Problem: Second harmonic with nrf905.
I used nRF905 and exact recommended design&layout in the datasheet. Now, it is said that there are 2. order harmonics @1736MHz, more powerful than the original signal. Moreover, there are another harmonics about @900MHz which is not meaningful. I have a transformer on the board (220v/10V), then, a 3.3V LDO that powers all the MCU. I used nrf905 at full power, my communcation was good, even the coverage was fine.
I found something like that: A CMOS power output stage (nRF905/nRF9E5) has different characteristics than a Bipolar power output stage (nRF902/nRF903/nRF904), and will generate increased second harmonic level when transmitting at a high power level. This increased second harmonic level must be attenuated in the antenna matching network and the antenna itself.
What should I do? I thought the design layout in the datasheet (matching circuit etc.) was ok.
