A spec without defining the source impedance and load impedance for each of multiple outputs is not a spec.
Nor is max load 50 Ohms a spec. nor is it a pulse with 1ns rise time.
If you model an ideal voltage source, load does not matter with tolerance.
But a true voltage source contradicts a 50 Ohm source with <1ns rise time.
Hence what spec!
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Before starting any design ( my frequent rant) you must write your own Design Spec.
If duplicating this instrument, ensure this is what you need, and we don't start chasing skinny little rats late into the design....
- for example this product has a rise time < 1ns with differential outputs +,- Is that what you will do?
if the signal risetime is at least seven times faster than the risetime of the oscilloscope vertical system, the displayed (observed) waveform will have a
risetime that is very close to the risetime of the vertical system. ...
If a fast-step signal produces a crt display with little or no overshoot or ringing, the product of oscilloscope risetime and oscilloscope bandwidth should result in a factor whose value lies between 0.329 and 0.350.
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I did not mean to cause you any problems Spec, I hope this is not my fault. My confusion on the circuit should not be your problem, it is mine. Having members who are willing to devote their personal time to help other people solve problems is a good thing, and should be encouraged, so I apologize for any trouble or hard feelings I may have caused.Apologies Tony I have obviously done bad. The trouble is being a newbee I dont understand the form: I just focus on the electronics and forget the wider issues. Perhaps ask admin to delete my posts and as they are might be misleading.
I did not mean to cause you any problems Spec, I hope this is not my fault. My confusion on the circuit should not be your problem, it is mine. Having members who are willing to devote their personal time to help other people solve problems is a good thing, and should be encouraged, so I apologize for any trouble or hard feelings I may have caused.
No Worries spec welcome to the group. Your depth of experience and insight is always welcome. I have always tried to think outside the box, which helped me do the impossible in my career and make anything work. So I like to share my experiences from that perspective.I did not mean to cause you any problems Spec, I hope this is not my fault. My confusion on the circuit should not be your problem, it is mine. Having members who are willing to devote their personal time to help other people solve problems is a good thing, and should be encouraged, so I apologize for any trouble or hard feelings I may have caused.
You will probably want to use miniature semi-rigid coax for routing to SMA connectors on board, if not front panel mounted., and use GETEK or quality Polyamid PCB material rather than cheap FR4.
This is pretty standard for high quality instruments.
Return loss is far better for precise signal quality. It's not hard to make. When I made a calibration jig for testing up to 6GHz, an RF design Engineer at Motorola in Arizona showed me how to test their LNA and difference in quality of connectors and cable is not visible to the naked eye can be significant even at 1 GHz.
Well, it's not production and about 800Mhz max, so I can prob get by with vanilla FR-4, I'll try to get some 1mm or 1/32" FR4 to do stripline.
I don't think you would want to go stripline as that would force you to buy a 4 layer board since the stripline is sandwiched between two layers. Not only that, but most of the times the transmission line impedance will not be matched to the load so some sort of tuning is required usually adding a matching circuit at the load like series L, shunt C. You really have a tough time tuning Stripline as it is a inner layer.Well, it's not production and about 800Mhz max, so I can prob get by with vanilla FR-4, I'll try to get some 1mm or 1/32" FR4 to do stripline.
Tony, I think you got me confused with Spec since you replied to my post and not Specs.No Worries spec welcome to the group. Your depth of experience and insight is always welcome. I have always tried to think outside the box, which helped me do the impossible in my career and make anything work. So I like to share my experiences from that perspective.
FR1 is just a lower flame retardant spec because it is cellulose based with epoxy and not very strong so no PTH and poor dimensional stability needed for stripline.
Materials with lower values of permittivity are increasingly needed for high-frequency applications.
Figure 1 plots both permittivity and loss characteristics for a range of materials, from which it can be
seen that lower values and losses than conventional epoxy-glass boards are really only available by
using laminates based on cyanate esters or PTFE.
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If you have some material etched, try seeing if it gets hot in a microwave oven ( no copper) or if it bursts into flames it has a poor loss tangent or dissipation factor and will give poor results for controlled impedance fast rise time signals.
Can you see 0.25% on a o-scope?How would I go about producing super precision ref Vs with 0.25% precision?
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