Re: [time-nuts] Opamp datasheet noise specs and their relation to phase noise
Thanks Charles. That should keep me busy for a while. :) On 14 March 2015 at 01:51, Charles Steinmetz csteinm...@yandex.com wrote: Stephan wrote: Any good texts on the subject that you can recommend? I don't own any texts with comprehensive discussions of AM to PM conversion or low-PN design. The best sources will most likely be papers. Some good search terms are AM to PM conversion (or AM/PM conversion) and low phase noise design (or low PN design). Here are a few to get you started: The Art of Phase Noise Measurement (Scherer, Hewlett Packard, 1985) www.thegleam.com/ke5fx/Scherer_Art_of_PN_measurement.pdf Phase Noise and AM Noise Measurements in the Frequency Domain (Lance, et al., 1984) http://tf.nist.gov/general/tn1337/Tn190.pdf RF and Microwave Phase Noise Measurement Seminar (HP, 1985) www.thegleam.com/ke5fx/HP_PN_seminar.pdf Phase Noise Measurement Using the Phase Lock Technique (Motorola AN1639, 1999) www.datasheetarchive.com/AN1639-datasheet.html Phase Noise in RF and Microwave Amplifiers (Boudot, Rubiola, 2010) arxiv.org/pdf/1001.2047 Origin of 1/f PM and AM Noise in Bipolar Junction Transistor Amplifiers http://tf.nist.gov/timefreq/general/pdf/1134.pdf Guidelines for designing BJT Amplifiers with Low 1/f PM and AM Noise http://tf.nist.gov/timefreq/general/pdf/1139.pdf PM Noise Generated by Noisy Components http://tf.nist.gov/timefreq/ general/pdf/1244.pdf Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opamp datasheet noise specs and their relation to phase noise
Stephan wrote: Any good texts on the subject that you can recommend? I don't own any texts with comprehensive discussions of AM to PM conversion or low-PN design. The best sources will most likely be papers. Some good search terms are AM to PM conversion (or AM/PM conversion) and low phase noise design (or low PN design). Here are a few to get you started: The Art of Phase Noise Measurement (Scherer, Hewlett Packard, 1985) www.thegleam.com/ke5fx/Scherer_Art_of_PN_measurement.pdf Phase Noise and AM Noise Measurements in the Frequency Domain (Lance, et al., 1984) http://tf.nist.gov/general/tn1337/Tn190.pdf RF and Microwave Phase Noise Measurement Seminar (HP, 1985) www.thegleam.com/ke5fx/HP_PN_seminar.pdf Phase Noise Measurement Using the Phase Lock Technique (Motorola AN1639, 1999) www.datasheetarchive.com/AN1639-datasheet.html Phase Noise in RF and Microwave Amplifiers (Boudot, Rubiola, 2010) arxiv.org/pdf/1001.2047 Origin of 1/f PM and AM Noise in Bipolar Junction Transistor Amplifiers http://tf.nist.gov/timefreq/general/pdf/1134.pdf Guidelines for designing BJT Amplifiers with Low 1/f PM and AM Noise http://tf.nist.gov/timefreq/general/pdf/1139.pdf PM Noise Generated by Noisy Components http://tf.nist.gov/timefreq/general/pdf/1244.pdf Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opamp datasheet noise specs and their relation to phase noise
Thank you Charles for the detailed answer. Any good texts on the subject that you can recommend? At the moment I have the books written by Motchenbacher and Henry Ott. NIST papers are another obvious source, but sometimes it is a little hard to fill in, or understand, the details without adequate pre-knowledge/experience. Regards, Stephan. On 6 March 2015 at 23:01, Charles Steinmetz csteinm...@yandex.com wrote: Stephan wrote: Opamp noise is usually specified in its datasheets as input voltage noise, V/sqrt(Hz), and input current noise, A/sqrt(Hz) versus frequency, Hz. Actually, those are the voltage and current noise *densities*. I'm not trying to be gratuitously picky, it's just that casual designers' understanding of noise, and their noise calculations, often come to grief because of just this kind of confusion. Is it possible to estimate the opamp's phase noise at a specific frequency (say a sinusoid at 10MHz or 100MHz) from these curves? No, not really, because: I'm assuming it can be seen as amplitude noise that is converted to phase noise. Correct. Some of the output noise of the amplifier is converted to phase noise directly -- meaning, any instantaneous measurement of the sine wave has an uncertainty in both amplitude and time due to the added noise. BUT this is not the main AM to PM conversion problem. The input noise (typically, but not exclusively at baseband rather than at the RF frequency) also modulates the operating parameters of the amplifier itself (typically, but not exclusively by modulating internal device capacitances), causing the amplifier's frequency response at RF to be modulated in synchronism with the noise -- which modulates the phase of the RF being amplified or processed by the amplifier. This process is different for every amplifier topology, so there is no way to calculate phase noise from the amplifier noise specifications without much, much more information (specifically, a very detailed model of the amplifier based on very detailed models of its component parts). It needs to be measured. [There may be nonlinear modeling software capable of making a first approximation, but I'm not aware of any.] Since the AM to PM conversion is most troublesome at baseband, PN is reduced by using devices with low noise at low frequencies (especially flicker or 1/f noise) and by making the internal amplifier gain low at low frequencies, for example by shunting low frequencies to ground with inductors where possible. Which in turn make it seem to me that it is dependent on the slope of the zero-crossing. Meaning it is dependent on signal amplitude and frequency? Not relevant. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Opamp datasheet noise specs and their relation to phase noise
Stephan wrote: Opamp noise is usually specified in its datasheets as input voltage noise, V/sqrt(Hz), and input current noise, A/sqrt(Hz) versus frequency, Hz. Actually, those are the voltage and current noise *densities*. I'm not trying to be gratuitously picky, it's just that casual designers' understanding of noise, and their noise calculations, often come to grief because of just this kind of confusion. Is it possible to estimate the opamp's phase noise at a specific frequency (say a sinusoid at 10MHz or 100MHz) from these curves? No, not really, because: I'm assuming it can be seen as amplitude noise that is converted to phase noise. Correct. Some of the output noise of the amplifier is converted to phase noise directly -- meaning, any instantaneous measurement of the sine wave has an uncertainty in both amplitude and time due to the added noise. BUT this is not the main AM to PM conversion problem. The input noise (typically, but not exclusively at baseband rather than at the RF frequency) also modulates the operating parameters of the amplifier itself (typically, but not exclusively by modulating internal device capacitances), causing the amplifier's frequency response at RF to be modulated in synchronism with the noise -- which modulates the phase of the RF being amplified or processed by the amplifier. This process is different for every amplifier topology, so there is no way to calculate phase noise from the amplifier noise specifications without much, much more information (specifically, a very detailed model of the amplifier based on very detailed models of its component parts). It needs to be measured. [There may be nonlinear modeling software capable of making a first approximation, but I'm not aware of any.] Since the AM to PM conversion is most troublesome at baseband, PN is reduced by using devices with low noise at low frequencies (especially flicker or 1/f noise) and by making the internal amplifier gain low at low frequencies, for example by shunting low frequencies to ground with inductors where possible. Which in turn make it seem to me that it is dependent on the slope of the zero-crossing. Meaning it is dependent on signal amplitude and frequency? Not relevant. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
