Bill,
It's time to change the subject title...to "How are IMDs created".
Adding a filter after a nonlinear process such as a mixer, will do no good
since the IMD has already been generated by the non linear element (and the
harmonic).
I don't see the point of the using a filter. Besides where would you put it?
I am considering taking a spectrum analyser and see if I see harmonics and IMDs
at the same time when hard mixing. That should help settle the issue. If there
are no harmonics and only IMDs you are right.
We can resume when you are up to it and feeling better. I am very interested in
the subject and welcome the interaction. Thanks, this part of learning after
all....
regards and 73s
chirs kb3bf
> I have one other thing to say.
> By thinking of these as separate processes that is the production of second
> harmonics and then mixing with the fundamental it is easy to see how one
> could think that by filtering out the second harmonics a class C amplifier
> could be made linear. That is that it would pass the two-tone test.
> However, most of us know that is not correct. Other wise any class C
> amplifier with a tuned output would be linear. I am happy that you read so
> much. But, I prefer to think for myself when I am looking for the answers
> to questions that I don't think have been adequately answered.
> Another confusing matter is that people often mix up intermodulation
> distortion and cross modulation, they are both produced by odd order terms
> in a polynomial but are very different effects. If you look at the math you
> will see that they are separate terms after the total expansion of the
> original expression.
>
> 73
> Bill wa4lav
>
>
> At 03:13 AM 1/2/2004 +0000, you wrote:
> >The rerefences I use come from Steven Maas, see below some of them.
> >I would welcome you sending me your derivations, it will be interesting to
> >compare notes, since I am not following what you are saying.
> >
> >73's
> >chris kb3bf
> >
> >
> >Dr. Stephen A. Maas
> >Selected Publications
> >Books and Book Chapters
> >S. Maas, Nonlinear Microwave Circuits, IEEE Press, New York, 1996.
> >
> >S. Maas, Microwave Mixers, Second Edition, Artech House, Norwood, MA, 1993.
> >
> >S. Maas, "Mixers for Wireless Applications," in L. Larsen, ed., RF and
> >Microwave Circuit Design for Wireless Communications, Artech House,
> >Norwood, MA, 1996.
> >
> >S. Maas, The RF and Microwave Cookbook, Artech House, Norwood, MA, 1998.
> >
> >Publications in Refereed Journals
> >S. Weinreb, M. Balister, S. Maas, and P. J. Napier, "Multiband Low Noise
> >Receivers for a Very Large Array," IEEE Trans. Microwave Theory Tech.,
> >vol. MTT-25, no. 4, pp. 243-8 (April, 1977).
> >
> >S. Maas, "Theory and Analysis of GaAs MESFET Mixers," IEEE Trans.
> >Microwave Theory Tech., vol. MTT-32, no. 10, pp. 1402-6 (Oct., 1984).
> >
> >S. Maas, "Design and Performance of a 45 GHz Active HEMT Mixer," IEEE
> >Trans. Microwave Theory Tech., vol. MTT-34, no. 7, pp. 799-803 (July, 1986).
> >
> >S. Maas, "Two-Tone Intermodulation in Diode Mixers," IEEE Trans. Microwave
> >Theory Tech., vol. MTT-35, no. 3, pp. 307-14 (March, 1987).
> >
> >S. Maas, "A GaAs MESFET Mixer with Very Low Intermodulation," IEEE Trans.
> >Microwave Theory Tech., vol. MTT-35, no. 4, pp. 425-9 (April, 1987).
> >
> >A. M. Crosmun and S. Maas, "Minimization of Intermodulation Distortion in
> >GaAs MESFET Small-Signal Amplifiers," IEEE Trans. Microwave Theory Tech.,
> >vol. MTT-37, no. 9, pp. 1411-7 (Sept., 1989).
> >
> >S. Maas and D. Neilson, "Modeling MESFETs for Intermodulation Analysis of
> >Mixers and Amplifiers," IEEE Trans. Microwave Theory Tech., vol. MTT-38,
> >no. 12, pp. 1964-1971 (Dec., 1990).
> >
> >S. A. Maas, D. Tait, and B. Nelson, "Intermodulation in Heterojunction
> >Bipolar Transistors," IEEE Trans. Microwave Theory Tech., vol. MTT-40, no.
> >3, pp. 442-8, (March, 1992).
> >
> >S. A. Maas and K. W. Chang, "A Broadband, Planar, Doubly Balanced
> >Monolithic Ka-Band Diode Mixer," IEEE Trans. Microwave Theory Tech., vol.
> >MTT-41, no. 12, pp. 2330-2335, (December, 1993).
> >
> >R. S. Virk and S. A. Maas, "Modeling MESFETs for Intermodulation Analysis
> >in RF Switches," IEEE Microwave and Guided-Wave Letters, vol. 4, no. 11,
> >pp. 376-8 (Nov., 1994).
> >
> >S. A. Maas, "Third-Order Intermodulation Distortion in Cascaded Stages,"
> >IEEE Microwave and Guided-Wave Letters, vol. 5, no. 6, pp. 189-91, June,
> >1995.
> >
> >S. A. Maas, "Volterra Analysis of Spectral Regrowth," IEEE Microwave and
> >Guided-Wave Letters, vol. 7, no. 7, July, 1997.
> >
> >Conference Publications
> >S. A. Maas, "A 45 GHz Low-Noise HEMT Mixer," European Microwave Conference
> >Digest, 1985.
> >
> >S. A. Maas, "A General-Purpose Computer Program for the Volterra-Series
> >Analysis of Nonlinear Microwave Circuits," IEEE MTT-S International
> >Microwave Symposium Digest, pp. 311-314, 1988.
> >
> >S. A. Maas, "A GaAs MESFET Balanced Mixer with Very Low Intermodulation,"
> >IEEE MTT-S International Microwave Symposium Digest, pp. 895-8, 1987.
> >
> >S. A. Maas and D. Neilson, "Modeling MESFETs and Diodes for
> >Intermodulation Calculations," Proceedings of the First International
> >Workshop on Integrated Nonlinear Microwave and Millimeter-Wave Circuits,
> >University of Duisburg, Duisburg, W. Germany 1990 (Invited Paper).
> >
> >S. A. Maas, "How to Model Intermodulation Distortion," Invited Paper, IEEE
> >MTT-S International Microwave Symposium Digest, pp. 149-151, 1991.
> >
> >S. A. Maas and Y. Ryu, "A Broadband, Planar, Monolithic Resistive
> >Frequency Doubler," IEEE Microwave and Millimeter-Wave Monolithic Circuits
> >Symposium Digest, pp. 443-6, 1994.
> >
> >R. Katz, S. Maas, A. Sharma, and D. Smith, "A Novel Monolithic HEMT
> >Harmonic Mixer at Q-Band," IEEE Microwave and Millimeter-Wave Monolithic
> >Circuits Symposium Digest, pp. 39-42, 1995.
> >
> >K. Hubbard, K. MacGowan, C. Kau, D. Smith, and S. Maas, "A Family of Low
> >Cost, High Performance HEMT MMICs for Commercial DBS Applications," IEEE
> >Microwave and Millimeter-Wave Monolithic Circuits Symposium Digest, pp.
> >133-136, 1995.
> >
> >S. Maas, "Planar Monolithic Microwave and Millimeter-Wave Circuits,"
> >Invited Paper, Proceedings of the ESA Workshop on Millimeter-Wave
> >Technology and Applications, p. 8.1.1, ESTEC, Nordwijk, The Netherlands,
> >1995.
> >
> >M. Case, S. A. Maas, et al., "An X-Band Monolithic Active Mixer in SiGe
> >HBT Technology," IEEE MTT-S International Microwave Symposium Digest, 1996.
> >
> >S. A. Maas, M.Kintis, F. Fong, and M. Tan, "A Broadband Planar Monolithic
> >Ring Mixer," IEEE Microwave and Millimeter-Wave Monolithic Circuits
> >Symposium Digest, 1996.
> >
> >S. A. Maas et al., "An 18-40 GHz Monolithic Ring Mixer," IEEE RF IC
> >Symposium Digest, 1998.
> >
> >Publications in Trade Journals
> >S. A. Maas, "Analysis and Optimization of Nonlinear Microwave Circuits by
> >Volterra Series," Microwave J., vol. 33, no. 4, p. 245 (April, 1990).
> >
> >S. A. Maas, "Microwave Mixers in the 90's," Microwave J., (Invited paper
> >for a special issue, Sept. 1990).
> >
> >S. A. Maas, "The Star Mixer," Microwave J., vol. 36, no. 7, pp. 36-46
> >(July, 1993).
> >
> >S. A. Maas, "The Diode Ring Mixer," RF Design, vol. 16, no. 11, p. 54
> >(Dec. 1993).
> >
> >S. A. Maas, "Nonlinear RF Circuit Analysis," RF Design, vol. 18, no. 3, p.
> >58 (March, 1995).
> >
> > > You know this misconception probably has come from the trig identity
> > > generally used to expand (Cos A + Cos B)^3.
> > > Which is the same one I use. However, it could be done with different
> > > identities. These processes are taking place simultaneously.
> > > It is not that a pair of terms are squared to produce a second harmonic
> > and
> > > then multiplied by the fundamental. It is just that in doing the math we
> > > expand the terms a little bit at a time.
> > >
> > > 73
> > > Bill wa4lav
> > >
> > >
> > >
> > > At 09:48 PM 1/1/2004 -0500, rfdude@COMCAST.NET,amps@contesting.com wrote:
> > > >You can see from the entire expansion that all three of the effects are
> > > >there. And one of the most interesting one is the cross modulation term.
> > > >Here you can see that the amplitude of one signal affects the
> > amplitude of
> > > >another.
> > > >
> > > >73
> > > >Bill wa4lav
> > > >
> > > >
> > > >At 09:42 PM 1/1/2004 -0500, rfdude@COMCAST.NET wrote:
> > > >>That is incorrect. If you wish to look over the math you will see the
> > > >>process that actually produces these products. There are actually 3
> > > >>effects caused by the odd terms. Harmonics, IMD products and cross
> > > >>modulation. These are produced simultaneously and if you filter out one
> > > >>or some it does not affect the others. Frequency Mixing is performed by
> > > >>the even order terms of the polynomial. You are using simply a binomial
> > > >>expansion and not a complete Taylor expansion of the non-linear
> > > >>characteristic curve.
> > > >>
> > > >>73
> > > >>Bill wa4lav
> > > >>
> > > >>
> > > >>At 02:12 AM 1/2/2004 +0000, rfdude@COMCAST.NET wrote:
> > > >>>Bill wrote:
> > > >>>*IMD is caused by the odd order terms of the polynomial ( output
> > > >>>voltage/input voltage) of a device. The harmonics of these can terms
> > ( 3rd,
> > > >>>5th etc harmonics) can easily be filtered but the near by IMD products
> > > >>>cannot since they are KHz or less from each other. Many think IMD is
> > due to
> > > >>>frequency mixing of harmonics but it is not, the additional
> > frequencies are
> > > >>>created in the device with out the aid of harmonics.
> > > >>>......................................................................
> > > >>>
> > > >>>
> > > >>>Just to set the record straight: IMD products ARE the mixing terms of
> > > >>>the the "harmonics" with the "fundamental(s) (correct for the lowest
> > > >>>order IMDs)".
> > > >>>
> > > >>>For example for a two tone case, F1 and F2, the first close-in-band
> > IMDs
> > > >>>are: 3*F2squared-F1 and 3*F1squared-F2, (F2squared is the 2nd harmonic
> > > >>>of F2, and so on....). Ignoring the amplitude term, this leads to the
> > > >>>3rd order IMD products: 2F2-F1 and 2F1-F2.
> > > >>>
> > > >>>The harmonics are part of the picture and are generated when the
> > > >>>fundamentals are raised to the higher power(s) of the binomial
> > expansion.
> > > >>>
> > > >>>The lowest order IMDs are created when the harmonics are mixed with the
> > > >>>fundament(s). For higher order IMD terms it is the mixing of also the
> > > >>>harmonics among themselves. These are the cross terms of the binomial
> > > >>>expansion.
> > > >>>
> > > >>>Only the cross term of the quadratic gives the desired beat products
> > > >>>because none of the terms are raised to a higher power (n=1) (no
> >
> > > >>>harmonics are involved). All the other cross terms of the binomial are
> > > >>>part of the IMD baggage.
> > > >>>
> > > >>>So harmonics are part of the picture in generating IMDs.
> > > >>>
> > > >>>Wonder why we use a "switch" for mixing instead of a true multiplier?
> > > >>>Well that another whole story.
> > > >>>
> > > >>>kb3bf, chris
> > > >>>
> > > >>> > IMD is caused by the odd order terms of the polynomial ( output
> > > >>> > voltage/input voltage) of a device. The harmonics of these can terms
> > > >>> ( 3rd,
> > > >>> > 5th etc harmonics) can easily be filtered but the near by IMD
> > products
> > > >>> > cannot since they are KHz or less from each other. Many think IMD is
> > > >>> due to
> > > >>> > frequency mixing of harmonics but it is not, the additional
> > > >>> frequencies are
> > > >>> > created in the device with out the aid of harmonics. If you are
> > > >>> interested
> > > >>> > in the math behind IMD and harmonic distortion and frequency mixing
> > > >>> > (
> > > >>> > algebra and trig.) I can attach to an email notes that one of my
> > > >>> students
> >
> > > >>> > put together from one of my classes. It is rather large for some
> > reason
> > > >>> > because I could not get it published to PDF without going to total
> > > >>> bit map.
> > > >>> >
> > > >>> > 73
> > > >>> > Bill wa4lav
> > > >>> >
> > > >>> >
> > > >>> > At 01:12 AM 1/2/2004 +0100, you wrote:
> > > >>> >
> > > >>> > >----- Original Message -----
> > > >>> > >From: "Bill Fuqua" <wlfuqu00@uky.edu>
> > > >>> > >To: <bill@wjschmidt.com>; "AMPS" <amps@contesting.com>
> > > >>> > >Sent: Friday, January 02, 2004 12:00 AM
> > > >>> > >Subject: Re: [Amps] 3.5 kV 2A REGULATED Power Supply: Schematic ?
> > > >>> > >
> > > >>> > >
> > > >>> > > > At 04:50 PM 1/1/2004 -0600, Dr. William J. Schmidt, II wrote:
> > > >>> > > > >Class A has less little IMD, class B has a lot. C would be
> > > >>> really nasty
> > > >>> > > > >if not
> > > >>> > > > >for output filtering (good tank circuit)
> > > >>> > > >
> > > >>> > > > C will have lots of IMD regardless of tank circuit. The tank
> > > >>> circuit only
> > > >>> > > > eleminates
> > > >>> > > > harmonics.
> > > >>> > >
> > > >>> > > ** not only eleminates ( most of ) harmonics, when cleaning up up
> > > >>> the sine
> > > >>> > >( RF ) as a f(Q ) of the tank.
> > > >>> > > I always believed IMD was included ! What am I missing
> > Bill ?
> > > >>> > >
> > > >>> > >Hpy 2004 to all.
> > > >>> > >
> > > >>> > >jos on4kj
> > > >>> > >
> > > >>> > >f> 73
> > > >>> > > > Bill wa4lav
> > > >>> > > >
> > > >>> > > >
> > > >>> > > >
> > > >>> > > > _______________________________________________
> > > >>> > > > Amps mailing list
> > > >>> > > > Amps@contesting.com
> > > >>> > > > http://lists.contesting.com/mailman/listinfo/amps
> > > >>> > > >
> > > >>> > > >
> > > >>> >
> > > >>> > _______________________________________________
> > > >>> > Amps mailing list
> > > >>> > Amps@contesting.com
> > > >>> > http://lists.contesting.com/mailman/listinfo/amps
> > >
> > > _______________________________________________
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> > > http://lists.contesting.com/mailman/listinfo/amps
>
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