Recently I've been working on a project for which I needed a 14GHz double-balanced mixer, however I'm on an extremely tight budget.
Luckily, most manufacturers provide free silicon samples these days, and Linear Tech (or rather, Analog Devices these days) is no exception. The LTC5548 is a pretty awesome MMIC, DC-6GHz IF, 1-12GHz LO, and 2-14GHz RF. It also includes a buffer so that you can use LO powers around the 0dBm mark instead of an ordinary mixer which might require.
Unfortunately, the evaluation board for the chip costs hundreds of dollars (~$300!) and I need multiple for my experiments.
So, I've designed my own:
And a render of the PCB:
I'm about to send this off to manufacture. For now, the repo (& design files) is at https://github.com/schnommus/rf-mixer
Once I get it back, I'll make some measurements and post an update!