how to design an UHF active bandpass filter

As stated in title, I would like to seek some advices to construct a circuit of UHF active bandpass filter.

requirements to meet:
must use jfet and not BJT.
frequency range within 200MHz to 500MHz (approximately).



I have tested a few circuits but the gain is -ve value and the frequency range is not fulfilled. Any circuit and suggestion?

Thanks.

You can you gm_C filter which is based on gyrator. So first you find the passive BPF that you want to implement and then substitute each inductor with a combination of gyrator and capacitor. It is on-chip or off-chip filter. If it is off-chip, you might have problems to fulfill this spec.

Dear Milad.
Would you please explain more about active BPF design.
I want to design a 160MHz filter with 10MHz bandwidth.
tnx

Hi Maryam,

At first you should specify the order of filter ( How much rejection, do you need in certain offset from center frequency? by knowing that, the order of filter can be found). Also there are several types of Filters such as butter worth, chebyshev and etc. Each type has certain properties.

By assuming that you have found the desired passive prototype filter, you can use two method for implementation of the filter:

1) Gyrator Based Filters: in which each inductor will be substituted by a gyrator and capacitor==> gm-C filter

2) Integrator Based Filter Design in which the state space equations of the prototype filter should be written and based on them by utilization of integrator (1/s), the active filter can be built.
2.1) The integrator can be built using op-amp c or gm_c.


A good tutorial about the second approach can be found here:

**broken link removed**

Thank you for your kind reply
I need to design a filter whose center frequency is on 160 MHz.
At your sent file the maximum frequency was at 10 MHz.
So I have a more question : Is this method is applicable to aforementioned frequency(160MHz)?
May I design an active filter at lower frequencies and then transfer it to my desired band?
Tnx