On 6 Feb 2005 20:10:23 -0800, "Jason" wrote:

|Hello All
|
|I posted topic about IP3 earlier and many people responded with
|excellent discussion.
|Today I wish to double check with you all about noise figure. It is
|something my friend check with me but I am not sure if it is right.
|Most importantly I want to know the Accumulative Noise Figure in blue
|colour.
|See the below link for visual
|
|http://www.geocities.com/jason_class/noise_q.jpg
|
|I purposely put my calculation there and hope you all can correct if I
|make any mistakes.
|Thank you in advance for your comment

What is in blue is correct. Your answer is not.

Once you have the cummulative noise factor and gain for the
amplifier/output filter it becomes the second stage for the
calculation of the input filter/amp cascade.

Note that the *gain* of the first stage (filter) is -2 dB (0.63)

Noise factor = 1.58 + ((3.548 - 1) / 0.63 = 5.62

NF = 10 log(5.62) = 7.5 dB.

Try this calculator:

http://www.marsport.demon.co.uk/tcalcxl.htm