Can i use LTC6945 as 5ghz VCO? And few questions on DDS, synth and DDS+VCO

Hello!
The first question is about using LTC6945 as 5ghz VCO. It is synthesizer+VCO chip, there is RFout pin. Can i use FET to amplify this output?

The second question about DDS,SYNTH,VCO chips. I want to clarify something out:

Synthezier chip to ... GHz - it can be used with external VCO to produce PLL (maybe with divider). So actually this chip itself can not produce RF output to ... GHz?

Synthezier+VCO chip to ... GHz - the same as above, but can be used without external VCO up to ... GHz? or with VCO+divider for Freq> SynthFreq.

DDS chip to ... GHz - can produse RF output, is it right?

The problem is, why we should use so many elements (external VCO, external Divider ic) to produce some frequency? I found some Analog Devices chip, but again requires external VCO, is there any simplier solution to get stable 5ghz?

There are many solutions to obtain 5GHz signal.I have found it but you may found better and more convenient.
http://www.hittite.com/products/view...ew/HMC820LP6CE

Because the vcos haven't bandwidth wider than an octave, producers cant use internal vco.
If you need continuous frequency, you can use hmc833,

Please suggest me some solution for narrow band.
I had an idea: use 1.000 GHz oscillator, find 5th harmonic and mix it with 5.abc GHz LO, extract "abc" freq offsetm then do tuning for "abc". But i read about harmonics, it is somewhat difficult to produce predictable results, especially for higher harmonics. I very like 5GHz fet oscillator, it is simple and low power/power consumption, but frequency changes all the time and never stops! I thinked about doubling, quadrupling, etc, but it needs filtering and amplification few times.
Also looked at some wifi chips, but power consumption and radiation is more than i need (3v 100mA).

If you look at the datasheet of the product which I suggested before, you'll see that it has a PLL and the frequency will never shift and spectral purity is almost perfect.