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Fundamental mixers (in the context of RF Electronics). What are they? What do they do?

http://www.hittite.com/products/view.html/view/HMC557LC4

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Fundamental means that the local oscillator is simply the difference between the IF and the input frequency. The other type is termed a sub-harmonic mixer, which is driven at a lower frequency which is multiplied in the mixer. The latter is used at much higher input frequencies, making it easier to generate the local oscillator signal.

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  • \$\begingroup\$ That's what I had guessed, but I wasn't sure. \$\endgroup\$
    – Jesse
    Nov 26, 2010 at 10:27
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The particular device you linked to is an RF mixer. It can work as an upconverter or downconverter, depending on the filtering used after the device.

An RF mixer takes an intermediate frequency signal and a local oscillator signal, and mixes them together. The output from an RF mixer is 4 different frequecies: A, B, A+B, and A-B (or B-A).

By filtering for what frequency you want (either A+B or A-B) you determine if the device is upconverting or downconverting.

I'll admit that I don't fully understand the significance of "fundamental", but if it's like with crystal oscillators, it means that the device doesn't operate at some harmonic of the local oscillator frequency ("overtone" in crystals.) It simply mixes the two signals exactly as presented to it.

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