HardwareChap
Junior Member level 1
I'm trying to match AD9361 differential RX at 1.3 GHz. I've got the S11 parameters for the RX LNA at 1.3 GHz:
freq magS11 angS11
1300000000 0.453016055876785 -82.7105506901038
I'm matching this to the balanced input of a balun. Am I right in thinking that the way to design the balanced impedance match is to first design a standard single ended matching network and then divide the passive components by 2 to match differentially? I plugged the complex conjugate S11 parameters into a matching calculator and got :
My concern is the unrealistic real world values (such as 585.3 pH). The RX pins of the AD9361 have 1.3 V on them, so need AC coupling caps to protect against DC shorts to ground. Which kind of sent me down this route:
Am I right in setting the Zs impedance (balun) to 50+j0? Am I right in matching to 0.453+j82.711? Is the conversion from single ended match to diff match circuit correct?
Extra info pages 62-68 of datasheet.
- - - Updated - - -
The demo board (schematic here, sheet 2, can word search for "RX1A" to jump to relevant part of the schematic) for this RF chip doesn't have any matching implemented because of the wide range it is expected to work with, so can't really use this as a guide.
freq magS11 angS11
1300000000 0.453016055876785 -82.7105506901038
I'm matching this to the balanced input of a balun. Am I right in thinking that the way to design the balanced impedance match is to first design a standard single ended matching network and then divide the passive components by 2 to match differentially? I plugged the complex conjugate S11 parameters into a matching calculator and got :
My concern is the unrealistic real world values (such as 585.3 pH). The RX pins of the AD9361 have 1.3 V on them, so need AC coupling caps to protect against DC shorts to ground. Which kind of sent me down this route:
Am I right in setting the Zs impedance (balun) to 50+j0? Am I right in matching to 0.453+j82.711? Is the conversion from single ended match to diff match circuit correct?
Extra info pages 62-68 of datasheet.
- - - Updated - - -
The demo board (schematic here, sheet 2, can word search for "RX1A" to jump to relevant part of the schematic) for this RF chip doesn't have any matching implemented because of the wide range it is expected to work with, so can't really use this as a guide.