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

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Terminator3

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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?
 

hosein_rabiee_g

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

Terminator3

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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).
 

BigBoss

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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.
 
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