Re: [time-nuts] sub harmonic VCO locking
Hi Attila thanks for your input. and thanks for the links ! I'll meet my low-spec option using ADF4356 integer mode, and a 394 MHz off the self $2 SAW filter on the output. That is what I'll do for the moment. I have the ADF4356 here on a eval board ADI lent me. It is not bad for an internal VCO chip. makes 126/ 10k @ 400 megs. Actually the Hittite HMC1033 is slightly better but 26 weeks. Discrete VCO using a TriTech TEM resonator (Q=400 400 MHz) was good also, with integer PLL chip. Maybe use a ceramic resonator up at 1.6 GHz where there is more Q and the chips are designed for the 1-4 GHz VCO input (LTC6945 etc) When I need to get the 5kHz to 100kHz noise down, I'l probably go for direct multiplication. 73 On 8/1/2020 2:06 PM, Attila Kinali wrote: On Thu, 30 Jul 2020 21:56:42 +1000 glen english LIST wrote: - a double-double-double could work, but my experience is for x2 x2 x2 I really need to filter well at each stage to avoid sum and difference products.. which might be OK for this application , especially if I filter really well after the first x2 . but avoid if I can. filters at 908 MHz need space, and shield cans where it is going. Frequency multiplying would be probably the easiest to get low noise, followed by a well designed PLL system. Though -115dBc spurs is tough, - and I dont know too much about phase noise and SRD or varactor multipliers. but maybe that's an option. SDR are prety low noise. From NLTLs we know that varactor systems can exhibit increased flicker noise levels (probably due to bias point instability). - onboard VCO chip/PLLs have all sorts of unrelated spurs in the output. - sure I can use a good PLL and a external VCO, but if my N value is fixed, and I can use injection locking, why bother with the PLL chip that is likely to introduce PD related spurs anyway. The generic way in this case is to build a PLL using frequency multiplier for the reference and a narrow loop filter after the phase detector. Placing zeros at the multiples of the (unmultiplied) reference frequency in the loop filter will reduce the spurs quite considerably. Injection locking is finicky. To injection lock, the resonator has to be pretty much on frequency to begin with, and kept that way. But unlike with other systems, you have no feedback system where get information how far off you are to control the frequency. Unless you build a hybrid system of an oscialltor with a Pound lock[5,6] (e.g. like cryogenic sapphire oscillators use[7]) You want to read Adler's paper[1] at the very least before you start. A look at the work byHuntoon/Weiss[2] and Kurokawa[3,4] is probably also beneficial. Attila Kinali [1] "A Study of Locking Phenomena in oscillators", by Robert Adler, 1946 (reprinted 1973) [2] "Synchornization of Ocillators", By Huntoon and Weiss, 1947 [3] "Injection Locking of Microwave Solid-State Oscillators", by Kurokawa, 1973 [4] "Noise in Synchronized Oscillators", by Kurokawa, 1968 [5] "Electronic Frequency Stabilization of Microwave Oscillators", by Pound, 1946 http://dx.doi.org/10.1063/1.1770414 [6] "Frequency-Stabilized Oscillator Unit Notes and Instructions", by Lawrance, 1946 https://dspace.mit.edu/bitstream/handle/1721.1/5024/1/RLE-TR-022-14254857.pdf [7] "An Ultra-Low Noise Microwave Oscillator Based on a High-Q Liquid Nitrogen Cooled Sapphire Resonator", by Woode, Tobar, Ivanov, 1995 ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] sub harmonic VCO locking
On Thu, 30 Jul 2020 21:56:42 +1000 glen english LIST wrote: > - a double-double-double could work, but my experience is for x2 x2 x2 I > really need to filter well at each stage to avoid sum and difference > products.. which might be OK for this application , especially if I > filter really well after the first x2 . but avoid if I can. filters at > 908 MHz need space, and shield cans where it is going. Frequency multiplying would be probably the easiest to get low noise, followed by a well designed PLL system. Though -115dBc spurs is tough, > - and I dont know too much about phase noise and SRD or varactor > multipliers. but maybe that's an option. SDR are prety low noise. From NLTLs we know that varactor systems can exhibit increased flicker noise levels (probably due to bias point instability). > - onboard VCO chip/PLLs have all sorts of unrelated spurs in the output. > > - sure I can use a good PLL and a external VCO, but if my N value is > fixed, and I can use injection locking, why bother with the PLL chip > that is likely to introduce PD related spurs anyway. The generic way in this case is to build a PLL using frequency multiplier for the reference and a narrow loop filter after the phase detector. Placing zeros at the multiples of the (unmultiplied) reference frequency in the loop filter will reduce the spurs quite considerably. Injection locking is finicky. To injection lock, the resonator has to be pretty much on frequency to begin with, and kept that way. But unlike with other systems, you have no feedback system where get information how far off you are to control the frequency. Unless you build a hybrid system of an oscialltor with a Pound lock[5,6] (e.g. like cryogenic sapphire oscillators use[7]) You want to read Adler's paper[1] at the very least before you start. A look at the work byHuntoon/Weiss[2] and Kurokawa[3,4] is probably also beneficial. Attila Kinali [1] "A Study of Locking Phenomena in oscillators", by Robert Adler, 1946 (reprinted 1973) [2] "Synchornization of Ocillators", By Huntoon and Weiss, 1947 [3] "Injection Locking of Microwave Solid-State Oscillators", by Kurokawa, 1973 [4] "Noise in Synchronized Oscillators", by Kurokawa, 1968 [5] "Electronic Frequency Stabilization of Microwave Oscillators", by Pound, 1946 http://dx.doi.org/10.1063/1.1770414 [6] "Frequency-Stabilized Oscillator Unit Notes and Instructions", by Lawrance, 1946 https://dspace.mit.edu/bitstream/handle/1721.1/5024/1/RLE-TR-022-14254857.pdf [7] "An Ultra-Low Noise Microwave Oscillator Based on a High-Q Liquid Nitrogen Cooled Sapphire Resonator", by Woode, Tobar, Ivanov, 1995 -- Science is made up of so many things that appear obvious after they are explained. -- Pardot Kynes ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] sub harmonic VCO locking
Hi Bob Yeah. because we essentially have a sampled system, so I expect multiples of the injection source. This is a sample rate clock, and so spurs that fall at 50% of the sample rate are OK. spurs that fall at 25% of the sample clock will appear in the PB. Which really tells me I need to have the injection oscillator at 1/2 the VCO freq . to avoid all problems. which means x2 x2 and assocated filtering before the injection. I'll go back to thinking about doubling/ multiplication and filtering. Given that spurs are on known frequencys, a set of symmetrically placed zeros either side of the output will generate a broad bandpass in the middle. No need for a sharp filter at least for the 1st pair of unwanted products maybe continue with you off list cheers On 31/07/2020 01:32, Bob kb8tq wrote: Hi On Jul 30, 2020, at 7:56 AM, glen english LIST wrote: Before I commit the soldering iron, can anyone share their sub-harmonic injection locking experiences ? I have to make 393.216 from 49.152 . Yes, lots of ways I know. injection locked at 1/8 of the frequency from the decent source. There wont be any issue of locking to the wrong harmonic, the VCO will be on the money.I was thinking of using a dielectric loaded TEM resonator or TEM coax line VCO . and why do this : ? - I need all the non related spurs to be > 115dB down. A sub-harmonic injection locked oscillator can / does have spurs at the injection frequency and it’s multiples …… Bob - a double-double-double could work, but my experience is for x2 x2 x2 I really need to filter well at each stage to avoid sum and difference products.. which might be OK for this application , especially if I filter really well after the first x2 . but avoid if I can. filters at 908 MHz need space, and shield cans where it is going. - and I dont know too much about phase noise and SRD or varactor multipliers. but maybe that's an option. - my attempts at generating low phase noise x6 with class C multipliers has been dismal. - onboard VCO chip/PLLs have all sorts of unrelated spurs in the output. - sure I can use a good PLL and a external VCO, but if my N value is fixed, and I can use injection locking, why bother with the PLL chip that is likely to introduce PD related spurs anyway. regards glen ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] sub harmonic VCO locking
Hi > On Jul 30, 2020, at 7:56 AM, glen english LIST > wrote: > > Before I commit the soldering iron, can anyone share their sub-harmonic > injection locking experiences ? > > I have to make 393.216 from 49.152 . > Yes, lots of ways I know. > > injection locked at 1/8 of the frequency from the decent source. > > There wont be any issue of locking to the wrong harmonic, the VCO will be on > the money.I was thinking of using a dielectric loaded TEM resonator or TEM > coax line VCO . > > and why do this : ? > - I need all the non related spurs to be > 115dB down. A sub-harmonic injection locked oscillator can / does have spurs at the injection frequency and it’s multiples …… Bob > > - a double-double-double could work, but my experience is for x2 x2 x2 I > really need to filter well at each stage to avoid sum and difference > products.. which might be OK for this application , especially if I filter > really well after the first x2 . but avoid if I can. filters at 908 MHz need > space, and shield cans where it is going. > > - and I dont know too much about phase noise and SRD or varactor multipliers. > but maybe that's an option. > > - my attempts at generating low phase noise x6 with class C multipliers has > been dismal. > > - onboard VCO chip/PLLs have all sorts of unrelated spurs in the output. > > - sure I can use a good PLL and a external VCO, but if my N value is fixed, > and I can use injection locking, why bother with the PLL chip that is likely > to introduce PD related spurs anyway. > > regards > > glen > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] sub harmonic VCO locking
Before I commit the soldering iron, can anyone share their sub-harmonic injection locking experiences ? I have to make 393.216 from 49.152 . Yes, lots of ways I know. injection locked at 1/8 of the frequency from the decent source. There wont be any issue of locking to the wrong harmonic, the VCO will be on the money.I was thinking of using a dielectric loaded TEM resonator or TEM coax line VCO . and why do this : ? - I need all the non related spurs to be > 115dB down. - a double-double-double could work, but my experience is for x2 x2 x2 I really need to filter well at each stage to avoid sum and difference products.. which might be OK for this application , especially if I filter really well after the first x2 . but avoid if I can. filters at 908 MHz need space, and shield cans where it is going. - and I dont know too much about phase noise and SRD or varactor multipliers. but maybe that's an option. - my attempts at generating low phase noise x6 with class C multipliers has been dismal. - onboard VCO chip/PLLs have all sorts of unrelated spurs in the output. - sure I can use a good PLL and a external VCO, but if my N value is fixed, and I can use injection locking, why bother with the PLL chip that is likely to introduce PD related spurs anyway. regards glen ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
