Cascade LNA in RX path of FEM to expand the IOT product range

RF Solutions RF Low Noise Amplifiers
1

I am currently working on the RF design for an IoT-based product and have integrated the Qorvo QPL9547 (2x LNA) in the RX path along with the Skyworks FEM (SKY66122) to expand the range. As we are still in the design phase and finalizing the schematic and PCB layout, I would appreciate your technical guidance on the following points:

  1. Effectiveness of 2x LNA in Cascade: Does placing two high-linearity LNAs in a cascade configuration significantly enhance the RF range, or are there diminishing returns in terms of range improvement?
  2. Impact of IIP3 in Real-World Noise Environments: When two high-linearity LNAs are used together, how does their Input Third-Order Intercept Point (IIP3) influence overall performance in noisy RF conditions?
2

Putting two QPL9547 in the RX path will give you a lot of gain, and you are probably going to have problems with linearity. Even a relatively small blocker is going to overload your front end and receiver. You will improve range, but only if there are no interfering signals. Often LNAs have a a bypass function so that you can lower the gain when large input signals are present. Note you would also need to improve the sensitivity of the radio at the other end of the link to improve range. There is a cascade calculator on the Qorvo web-site you can use. Cascade Calculator - Qorvo