Re: [time-nuts] Isolation achieved by opamp based isoamp?

: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im Auftrag von Stephan Sandenbergh Gesendet: Donnerstag, 21. November 2013 14:47 An: Discussion of precise time and frequency measurement Betreff: [time-nuts] Isolation achieved by opamp based isoamp? Hi, I'm curious about

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Stephan Sandenbergh Gesendet: Donnerstag, 21. November 2013 14:47 An: Discussion of precise time and frequency measurement Betreff: [time-nuts] Isolation achieved by opamp based isoamp? Hi, I'm curious about the level of isolation that is achieved by an opamp based isoamp. I'm referring

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Stephan, On 11/21/2013 02:46 PM, Stephan Sandenbergh wrote: Hi, I'm curious about the level of isolation that is achieved by an opamp based isoamp. I'm referring to ones described here on Bruce Griffiths' page: http://www.ko4bb.com/~bruce/IsolationAmplifiers.html Anyone has a number for

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Magnus wrote: An interesting article is here http://tf.boulder.nist.gov/general/pdf/498.pdf Note that Figure 2 and Figure 3 are reversed in that article (Figure 2 actually shows the NIST amp and Figure 3 shows the DeMarchi topology). The schematic shown does not disclose any components,

Re: [time-nuts] Isolation achieved by opamp based isoamp?

measurement Betreff: [time-nuts] Isolation achieved by opamp based isoamp? Hi, I'm curious about the level of isolation that is achieved by an opamp based isoamp. I'm referring to ones described here on Bruce Griffiths' page: http://www.ko4bb.com/~bruce/IsolationAmplifiers.html Anyone has

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Thanks for the spec. I suspected that it would be in that ball park. The discrete transistor type amplifiers achieve around 120dB or more at 10MHz. But, they are a lot more effort to implement than the opamp designs. I believe the transformer in this case is for ground loop isolation rather than

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Something that would be interesting to know is if certain opamps are better suited toward S12 isolation than others. I guess at the expense of noise floor and 1/f corner one could cascade two opamps to improve the S12 isolation further. As soon as you are looking at frequencies of 100MHz you are

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Stephan Sandenbergh wrote: Something that would be interesting to know is if certain opamps are better suited toward S12 isolation than others. I guess at the expense of noise floor and 1/f corner one could cascade two opamps to improve the S12 isolation further. The flicker noise corner

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Stephan wrote: The discrete transistor type amplifiers achieve around 120dB or more at 10MHz. Well, SOME discrete transistor amplifiers CAN achieve 120dB or more of reverse isolation, if everything is done properly. But 120dB or more takes careful attention to detail at every step -- it is

Re: [time-nuts] Isolation achieved by opamp based isoamp?

One thing to keep in mind is that isolation through shielding usually results in much greater capacitance to ground (actually to the shield) from both input and output windings. Therefore, the actual isolation in practice is totally driven by how good the ground to the shield is. At RF, any

[time-nuts] Isolation achieved by opamp based isoamp?

Try looking here. http://www.cliftonlaboratories.com/z1_buffer_amp.htm This opamp buffer has 80-90db isolation. Corby ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

[time-nuts] Isolation achieved by opamp based isoamp?

Hi, I'm curious about the level of isolation that is achieved by an opamp based isoamp. I'm referring to ones described here on Bruce Griffiths' page: http://www.ko4bb.com/~bruce/IsolationAmplifiers.html Anyone has a number for this? I've tried googling it, but the results are mostly filled

Re: [time-nuts] Isolation achieved by opamp based isoamp?

A good transformer has very high CMRR. The purpose of the interwinding shield is to prevent CM on the input swide, coupling through to the buffer input, and yes, it should be well grounded. However, even if the shield is not perfectly grounded, it greatly reduces the interwinding coupling

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Corby wrote: This opamp buffer has 80-90db isolation. That is typical at 5 to 10 MHz *if* (i) all of the splitting is done on the input side (i.e., each output has its own op amp), and (ii) the splitter and all of the construction (grounds, shielding, etc.) is done correctly. If any

Re: [time-nuts] Isolation achieved by opamp based isoamp?

Looking quickly at the prints on the site, the isolation is provided by the transformer, not the active circuitry. The transistors/op-amps are just buffers for the output. That means that the isolation is determined, for the most part, by the transformer design, so: A bifilar wound torroid