check in:

http://www.digikey.ca/products/en/integrated-circuits-ics/linear-amplifiers-instrumentation-op-amps-buffer-amps/687

is the best for low ferquency devices

Naveed.

You can estimate sensitivity as equal to = 10×log10(kTB)+NF+C⁄N

C/N is the desired carrier to noise ratio. NF is the noise figure of the amplifier.

plug into your numbers and choose a suitable amp.

we have developed a LNA using discrete components with  a NF of 1.0 dB.

-40 dBm is not much of a requirement. Just about any instrumentation amplifier with gain–bandwidth product of over 40MHz will do just fine.

There are also discrete solutions with BF862 that may do.

LT1793. It is an easy handled op amp from Liear Technologies.

Designed for low noise amplifiers. May be combined with BF862.