Transceiver chip impedance

[disisku_22]

hi,
will there be any changes in internal impedance or performance of RF transceiver chip if i use different stack up other than the reference design?. i am aware that different stack up will affects impedance of the RF traces/tracks but what about the transceiver chip alone?.


regards

 

[FvM]

As the term says, "internal impedance" is internal. Although it's not exactly constant over load variations, it should be approximately considered so.

The transceiver performance will be however affected by imperfect grounding and supply bypassing. The specified parameters are valid for a layout similar to the manfucaturers reference design.

 

[disisku_22]

thanks.. ok, if i maintain same the impedance what transceiver required by adjusting the RF trace Width and matching components, then i can choose different stackup?

 

[FvM]

Basically yes. My main concern would be about the distributed circuit elements modifying the matching network. If you are reproducing a reference design, a considerable change in effective substrate height (trace to ground plane) can matter a lot. Most likely, you would want to verify the matching and (possibly more critical) harmonic supression of your design in a measurement and adjust component values, if necessary. The most exact PA impedance determination is by load pulling anyway.