ADRF5515 channel to channel isolation

Dear Specialist,

          Do you have channelto channel isolation testing guaidance documents can be shared, how to configure the control signal.

         We try to test it with our experience but the result is quite different with the discription from datasheet.

Below is our test procedure,

1) set power tree for below ports, for unused ports such as Term-CHA, Term-CHB, tie to 50Ω load.

Pin

Setting

VDD1-CHA

5V

VDD1-CHB

5V

VDD2-CHA

5V

VDD2-CHB

5V

SWVDD-CHAB

5V

SWCTRL-CHAB

0V

BP-CHA

0V

BP-CHB

0V

PD-CHAB

0V

2) ADRF5515 work in High Gain mode,

VNA Port1 conncet to ANT_A, Port 2 connect to RXOUT-CHA and get the result  A;

VNA Port1 conncet to ANT_A, Port2 connect to  RXOUT-CHB then get the result B,

B-A is RXOUT-CHA to RXOUT-CHB isolation as below, in the datasheet the normal value is 45db.

Parents
  • 0
    •  Analog Employees 
    on Dec 30, 2020 8:18 AM 3 months ago

    Hi,

    Could you please share RXOUT_CHA to ANT_CHA gain and RXOUT_CHB to ANT_CHA leakage seperately? Lets review them both. Your calculation looks correct. 

    Do you use the evalboard or your own design? Is it possible for you to share the schematic and layout? Supply capacitors and pcb layout is critical to achieve the isolation. 

  • Hi,

    Also share our layout FYR~

    To be noticed that:

    1. Due to space limited, we put 1uF and 100nF capacitors at VDD_A, VDD_B and SWVDD paths on the mother board, and this LNA board is soldered to that mother board.
    2. The 300ꭥ and 100pF decouple capacitor of BP_A and BP_B is also populated on mother board due to the space limited on the LNA board.

  • 0
    •  Analog Employees 
    on Jan 12, 2021 9:15 AM 2 months ago in reply to Verti

    Thanks for sharing this.

    If possible I'd like to review the top layer metal gerber and vias which are not easily observed. A continuous ground plane with dense vias is known to improve the isolation. I noticed there are discontinuities on each corner of the part. 

    Also, 100pF should be close to the part and 100nF should be asselmbed afterwards. I assume your arrows have error, please confirm.  

Reply
  • 0
    •  Analog Employees 
    on Jan 12, 2021 9:15 AM 2 months ago in reply to Verti

    Thanks for sharing this.

    If possible I'd like to review the top layer metal gerber and vias which are not easily observed. A continuous ground plane with dense vias is known to improve the isolation. I noticed there are discontinuities on each corner of the part. 

    Also, 100pF should be close to the part and 100nF should be asselmbed afterwards. I assume your arrows have error, please confirm.  

Children