# Question about Microstrip Filters and Circuits?

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#### zoriyanj

##### Newbie level 3
Hello everyone, i have critical questions about this subject. In my case i used to design randomly which means when changing dimensions sometimes i obtain good result. But i don't know about way to from lumped elements starting. i studied papers but there was only approximation. no calculation. Please help me.

---------- Post added at 03:03 ---------- Previous post was at 02:52 ----------

Actually I think engineers used to design from Specification of Filter. in my case i used to design inversely. I have another question. if i have good pattern of Microstrip BPF how i can convert into Lumped elements. i tried richards and Kurodo transfom but it is not sufficient for me. If that design more complicated pattern how can i analyze it.

#### tony_lth

you can simulate in ADS, then form LC from S-paras. But why to convert microstrip into LC?

zoriyanj

### zoriyanj

Points: 2

#### zoriyanj

##### Newbie level 3
Thank you for Repying. I want to calculate first and after that design but i cannot. For example center frequency 3GHz BW 1GHz or something else. How can i form the shape and even if it has different substrate in which has 2 or more layers

#### tony_lth

In AWR, there is multilayer substrate model, you can select.
Your BW seems a little wide, but you can try using coupled line.
Set the original value as following: The length of coupled line is about 1/4lamda, and width is about 30~50 ohms.
And set variable optimising range, then do optimization. AWR will do all the job for you.

zoriyanj

### zoriyanj

Points: 2

#### zoriyanj

##### Newbie level 3
Thank you for your reply. I have another problem for stepped impedance resonator. how i can calculate stepped impedance resonator. for example center frequency 13Ghz BW 12-14Ghz. Return loss 30dB, insertion loss 1dB
i tried ADS LineCalc but it hasn't shown me result. in case of Line calculator can calculate stepped line,?

#### zoriyanj

##### Newbie level 3
Hi all, I need to design according to spec, Center frequency 12GHz<f0<14GHz, insertion loss<2.5dB, BW @ 1dB +-350MHz, BW @ 3dB +-400MHz, VSWR 1.7:1, Attenuation BW @ 15dB +-800MHz, Attenuation BW @30dB +-1600MHz, Attenuation BW @ 35dB +-3200MHz, I/O impedance 50Ohm, Max input power 2W, Maximum dimenssion 8X3X0.4mm.
It has 2 substrate Bottom is GaAs 200um, Above one is SiN 0.2um.
At First step I have to do? how can i estimate and synthsize width, and length with 2 layers? which software is good?

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