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Multiplier chains
In message , Alan Peake
writes amdx wrote: Here's an interesting simple circuit to generate odd harmonics. "New Topology Multiplier Generates Odd Harmonics" http://www.wenzel.com/pdffiles1/pdfs/RFDesign2.pdf Mike Yeah, saw that. Trouble is that I need EVEN harmonics If you want EVEN harmonics, then use the 'fullwave rectifier' circuit. This is essentially identical to what you use to rectify the mains, but it works at RF. One version is the simple bi-phase circuit, consisting of a ferrite input transformer (ratio 1 : 1+1) and two rectifying diodes. An alternative is the fullwave bridge version. I have used the former with great success to multiply by 2, 4 and even 6 but, of course, you get a lot less with the higher order harmonics. Also, the relative suppression of the even harmonics is less. Anyway, there was some interesting info on snap diodes etc. Makes me think that the diode used in the gear I have, aren't SRDs as these seem to be mainly for microwave use. I did get involved with a comb generator which used a single step recovery diode, driven at 6, 7 or 8MHz, to generate fairly equal amplitude harmonics (both odds and evens) to around 600MHz. The other info I gleaned was that it's easier to get low phase noise with straight multiplication than it is with PLLs. Not that I have an urgent need for low phase noise - but it's interesting nonetheless. Alan I didn't know that the "New Topology Multiplier Generates Odd Harmonics" circuit existed. It's every bit as simple as the fullwave rectifier circuit for generating even harmonic! -- Ian |
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