about RF superheterodyne receiver design

hi friends,
i have a question about a design that i made and there is someone who told me that it will be a mistake if i do such thing. in fact, i have a superheterodyne receiver with dual stage: there is a RF filer, LNA, Filter, (Mixer1 with LO1) to have an IF 1 GHz , gain amplifier 1 + filter 1, (Mixer2 with LO2) to have an IF2 of 30 MHz , gain amplifier 2 + filter 2, VGA and ADC.
in my design i used to have two amplifier having the same characteristics ( NF, Gain and IIP3) and also two mixers having the same characteristics too.
but, someone told me that the due the difference in the frequence range ( IF1= 1 GHz and IF2= 30 MHz) the design of the two amplifiers will not be correct.
so is it really true, and how could i alleviate this problem eventually??
an other question; could these amplifiers have the same ( NF, IIP3 and gain) but they are not the same in other charactéristics since i didn't begin the transistor level design?

Best regards,
imar

The difference between first IF and second IF is too high, and will be hard to suppress the second IF image frequency. This is not a big issue at this stage, because the increasing of total NF is not significant, as the first IF image is.

For system analysis using different NF, gain and IP3 amplifiers at different stages use the freeware AppCAD ( go to Signals-Systems/ NoiseCalc)

http://www.hp.woodshot.com/

thanks for the tool,
i made my system level design through ADS tool and results are convinient to the specifications.
for my design, the image suppression of the second IF is well done.
my unique problem, that i was told that the two amplifiers which has the same characteristics ( NF, IIP3 and gain) will not work well while trying to make the transistor level design and this is the question that i want to understand before passing to the transsistor level design because when i made my simulation with ADS, the two amplifiers Amp1 and Amp2 present good performances.
thanks for helping me to understand this point.

regards
imar

Sure is an issue designing two identical transistors (NF, IIP3, Gain) working at such frequency difference, but is not impossible.
If this is about RFIC design and the amplifiers are on the same die, there could be a problem making them equal in performances.
Before doing the system analysis has to run a transistor level evaluation to see what the limits in performances are.

So, i have to make the transistor design before saying that the systel level design will not work well after designing the two amplifiers.
an other thing that comes to my mind, to design an amplifier in RFIC, there is not only gain, NF and IIP3. that's why, the two amplifier could have approximatively the same NF, IIP3 and gain but they might differ in other characteristics which are not yet specified.
isn't it?
regards,
imar