BJT VHF frequency doubler circuits

Over-driving a transistor gives output rich in ODD harmonics.

An ordinary diff pair driven just right produces a nice second-order component... see the harmonic mixer patent on my website.

...Jim Thompson

hi all, I was wondering if anyone has a circuit design for a simple VHF frequency doubler.

cheers, Kevin.

Great! Do you know if a 2 pole low pass filter set above the desired freq would sufice to cut out the harmonics generated by the over drivin stage?

one idea is to think about a full wave rectifier bridge.

Jure Z.

Or a push-push doubler--two transistors, drive the bases differentially, and wire the collectors in parallel. All the odd-order stuff cancels, including the fundamental.

Cheers,

Phil Hobbs

good point! I was think square wave rich in odd harmonics.. for EVEN you need asymmetry about the time access..wave form shape.

A fet based unit pumping on a varactor load would distort nicely.

as for # poles... more poles will suppress the fundamental and thirds etc.. so you need to know how clean you need..

Marco

frequency

Geez! Just make a tuned circuit at the target frequency, and let the harmonics go to the bit bucket! Fr = 1/(2 * pi * sqrt(L * C)).

Good Luck! Rich [and I've heard that top-posting is frowned upon amongst da prose.]