overdrive a transistor so it is non-linear and tune the output tank to the desired output freq.
Mark
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- posted
18 years ago
BJT VHF frequency doubler circuits
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18 years ago
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
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
- posted
18 years ago
hi all, I was wondering if anyone has a circuit design for a simple VHF frequency doubler.
cheers, Kevin.
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18 years ago
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?
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18 years ago
one idea is to think about a full wave rectifier bridge.
Jure Z.
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18 years ago
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
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18 years ago
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
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- posted
18 years ago
On Mon, 27 Jun 2005 03:02:40 +0100, Kevin Doyle top-posted:
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.]