MultiStage FrontEnd Receiver Desing Using BF998

[adnan012]

hi,

I want to design a sensitive 3 stage receiver circuit for 40 MHz using BF998. Very narrow bandwidth (39-41MHZ) and maximum attenuation is required out of the band.

I need help in the following steps

Input filter design (type and order)
Biasing the BF998
impedance matching at input side .
Interstate matching
Output matching to NE612 mixer ic.

I can simulate the design in ADS 2009.

Regards

 

[BigBoss]

If you attempt to catch a certain degree of sensitivity, I recommend you to consider "Noise Matching" that will give you lower Noise Figure from that amplifier.
If the first stage of the chain is a Filter, the Insertion Loss of this filter will contribute directly into Noise Figure of the system so the first stage shouldn't have lossy elements.( the frequency is low so high quality compact components should be used to prevent high losses).

 

[adnan012]

Thanks for reply.

What is the sensitivity of NE602 or NE612 mixer ic? Can it receive -90dbm signal without any per-amplifier stage?

 

[BigBoss]

Thanks for reply.

What is the sensitivity of NE602 or NE612 mixer ic? Can it receive -90dbm signal without any per-amplifier stage?

I don't know and it depends on your bandwidth.But -90 dBm is pretty low and a LNA ought to be used.