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Slew Rate, Bandwidth, Settling time, rise time for high speed transipmedance amp

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Marco:
AFAICS a microchannel plate has 50 Ohm output. You don't need a TIA, you need a RF gain block.

If you don't care too much about gain flatness just pop a SPF5189 amplifier in there, you can get modules really cheap. Or for a bit better build quality this module which I assume is based on TQP3M9036 doesn't seem a bad deal.

Conrad Hoffman:

--- Quote from: T3sl4co1l on August 24, 2019, 08:05:31 pm ---....There is also a noise associated with capacitance, independent of system resistance, or bandwidth (they cancel out).  For 20pF at room temperature, this is 28uV....

Tim

--- End quote ---

I always thought pure capacitive or inductive reactances had no noise, though it seems like there should be at least some. How is this calculated?

Conrad

T3sl4co1l:

--- Quote from: Conrad Hoffman on August 25, 2019, 06:04:41 pm ---
--- Quote from: T3sl4co1l on August 24, 2019, 08:05:31 pm ---....There is also a noise associated with capacitance, independent of system resistance, or bandwidth (they cancel out).  For 20pF at room temperature, this is 28uV....

Tim

--- End quote ---

I always thought pure capacitive or inductive reactances had no noise, though it seems like there should be at least some. How is this calculated?

--- End quote ---

There must necessarily be a resistance somewhere -- otherwise you can't measure any signal at all (though you might be able to sense it parametrically, with other limitations).  That resistance gives the RC time constant and therefore the cutoff frequency, but it's also the noise source and therefore the noise level.  Noise over the total bandwidth happens to cancel out, giving the simple result. :)
https://en.wikipedia.org/wiki/Johnson–Nyquist_noise#Thermal_noise_on_capacitors

Tim

T3sl4co1l:

--- Quote from: Marco on August 25, 2019, 05:24:16 pm ---AFAICS a microchannel plate has 50 Ohm output. You don't need a TIA, you need a RF gain block.

If you don't care too much about gain flatness just pop a SPF5189 amplifier in there, you can get modules really cheap. Or for a bit better build quality this module which I assume is based on TQP3M9036 doesn't seem a bad deal.

--- End quote ---

And for that matter, hopefully the MCP is built in such a way that it has a transmission line structure.

For example, it might be a sinuous path over a ground plane, which has the bonus of allowing you to correlate propagation delay to impact location.

You're still very limited by noise, and may need to stack another MCP to get higher particle amplification, or something like that.

Tim

Marco:
In theory you could segment the anode for a MCP in say cm^2 pieces and bring multiple connections outside, that should allow you to use multiple very low impedance TIAs.

But given that in the other thread he mentioned connecting it to a Phillips lab amplifier he almost certainly just has coax coming from the device and he needs a RF amplifier. The TQP3M9036 has an almost unbelievably low noise which should bring the noise down by about 2x relative to the Phillips amplifier (for the same bandwidth, but it has far more bandwidth than the Phillips).

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