Hello,
I'm designing a Local Oscillator using LMX2581 for a first stage mixer. Our design demands the output frequency of 800 MHz to 1800 MHz.
My question is related to the layout design. Our intention is to fabricate the design in a FR4 PCB. When looking at the Figure 27. LMX2581 Layout Example in device datasheet, I can see the RFout pins are initially routed out from the device using, what seems like, ~7 mil PCB traces and then they became wider at the end. I'm guessing that the wider PCB trace corresponds to 50 ohm impedance.
Usually 50 ohm line width is calculated for a specific frequency. In my case, the bandwidth is 1 GHz. Therefore, what frequency should I use to calculate the trace width?
Also, when the trace width changed from high to low, wouldn't there be impedance mismatch and possible signal degradation? (I know practically maintaining the same trace width is not possible, but what is the effect)
Thank you.
