Help me design a wide lowpass filter

[vitan2]

Hello

I need to design lowpass filter to 500MHz and stop band is from to 600MHz to 3GHz.
Could you advise which structure fit on.

many thanx
V.

 

[chounglee]

Re: Wide Lowpass filter

Do you mean by bandpass filter?

 

[amicloud]

Re: Wide Lowpass filter

Perhaps you need to cascade two or three lowpass filters.
because commonly the stopband of lowpass filter can not be far away, often not bigger than 2times the passband edge(because the step impedances are not infinite high or low).

to extend your stopband you can use defected ground structure or use suspended stripline techniques.

Liu

 

[g579]

Re: Wide Lowpass filter

A normal lumped LP filter with 0603 size lumped element will work.
You should control the design with some simulator too.

 

[chounglee]

Re: Wide Lowpass filter

I miss understood that.

I agree with 0603 components. Also, check minicircuits out for low pass filter.

 

[kannadassan]

Wide Lowpass filter

In simple, as Amicloud told, the DGS structure can offer simple size of LPF, for I think the ground have to be etched about 10mm(for 5mm of a and b, it comes around 3GHz cut off frequecy). I believe, the ordinary stripline with 400mil length and 300 width with one open circuited stub of 400 mil length can give such LPF, for instead of DGS.. Amicloud!!

 

[ravisankar]

Re: Wide Lowpass filter

First choose lpf with 500MHz cut off and one more with 1.5GHZ cut off frequency(less elements)with lumped elements we can achive

But u r not mentioned the rejection value

please give the detailed specifications and mention the size requirement.
i may help u.