Simulation with transmission lines

Hello all,

I have designed a circuit in ADS which includes amplifiers and a bandpass filter. Filter is composed of lumped smt components. I have optimized the circuit for better S11 and S21 curves. Everything was fine up to this point. Then I started to design the layout and added transmission lines using MLINs and defined MSub. After this I went back to schematic to re-simulate. Now all my curves are messed up... I tried to optimize TL lengths and lumped element values but no luck. How can I obtain better results? I am using values for FR4 substrate. I didn't know that TLs would have a big impact on the circuit like this

Have you tried to simulate your filter by using Momentum EM simulator ? If you already have done it, it should normally work well..


Then, you should simulate them in co-simulation environment.I mean, your layout and your discrete components should be simulated simultaneously.

simulate them separately to see which one has problem

Try adjusting T-Line widths rather than lengths. And yes do try to simulate them in parts