On Sun, 21 Aug 2016 10:04:10 -0700 Alex Pummer <a...@pcscons.com> wrote:
> directional coupler/circulator could be made with high bandwidth [ up to > 1GHz ] operational amplifiers, that circulator will work from DC.. While this is a valid option, it would then become the element in the system that limits dynamic range. It's better to use a "noiseless" passive circuit that has very little distortion. Also keep in mind that even if the opamp has an GBW of 1GHz or more, the slewrate kicks in quite early and in this case would limit the maximum signal strength severely. There is a reason why GHz amplifiers use so much power. > driving A/D converter input asymmetrically; drive trough a > Guanella-choke, but match the output of the choke The Guanella balun, like all other transformer based baluns, has the same upper and lower frequency limits: The inductance sets the lower limit (more inductance -> lower frequency) and the loss in the ferrite sets the upper limit (non-linear and thus can be quite abrupt). Another issue here is symmetry of output over frequency (c.f. [1]). I don't know how good the Guanella baluns are in reality, but this is definitly something that should be looked at. Attila Kinali [1] http://www.markimicrowave.com/blog/2013/07/why-buy-a-high-quality-baluntransformer-for-an-analog-to-digital-converter-adc/ -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson _______________________________________________ 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.