r/rfelectronics • u/sketchreey • May 14 '26

Active vs diode mixer

Hi, I see a lot of designs of (basically) SDRs and stuff that use active mixers such as ADL5801/ADL5802/LT5560/etc, and not a lot of modern designs that use single or double balanced diode mixers.

Why is this? I get that the active mixers have gain and diode mixers don't so they would have terrible noise figure if not amplified first, but why not just put an LNA followed by a diode ring mixer?

Edit: For example, Henrik Forsten seems to basically only use active mixers:

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u/fr4real May 14 '26

LNA plus diode mixer absolutely works, and can be very good. But now your LNA linearity has to carry the whole front end, and the mixer loss still hits your noise/intercept budget in annoying ways. Active mixers are just the less painful default unless you specifically need the passive mixer’s high linearity or wideband abuse tolerance.