What is the advantages and disadvantages of using mixer as doubler?

[tony_lth]

I saw an example of using differential -mixer as freq doubler, what is the advantages and disadvantages of this method?

Can traditional mixer (non-differential-mixer) be used as freq doubler?

thanks.

 

[BigBoss]

I guess because of the linearity issues...
Just a guess...

 

[zorro]

Yes, a diode ring can be used.
I guess that the generation can be optimized with some phase difference between LO and RF inputs. For example, if RF would be square wave, it should be in quadrature with LO for maximum efficiency (if they are in phase, the 2nd order product would cancel).
As another possibility, you can use a push-push configuration.
Regards

Z

 

[tony_lth]

Using mixer as freq-doubler is an example from ADS: FreqDoubler_Gilbert. The following is the schematic, who can give more comment on it? Thanks.

 

[tony_lth]

I guess that if IF-freq is equal to LO-freq, the RF-freq is 2*LO-Freq. But there is DC current, so this maybe cause harm to mixer diode. Am I right?

 

[zorro]

Using mixer as freq-doubler is an example from ADS: FreqDoubler_Gilbert. The following is the schematic, who can give more comment on it? Thanks.

Is the mixer based in a Gilbert cell (as the file name suggests)?
Can you give a more detailed description if the mixer block?
I find strange the direct connection of the two ports (N and LO).
Regards

Z

 

[tony_lth]

The schematic is right, because I can run it and get the following results as output1 and output2.

Mixer.jpg is the mixer schematic, and it is Gilbert cell.

 

[jiripolivka]

The two-diode balanced mixer structure can act as a good efficiency doubler. Diodes alternately open and close, so from the input frequency the second harmonic is generated (in fact, all even harmonics). The IF line is not used. Look at "www.spaceklabs.com"; we use such doublers and quadruplers as commercial models.
If you need a frequency tripler, diodes are connected "anti-parallel" and generate the third and odd harmonics.
Similar structures are used in MMICs.