[time-nuts] More on paralleling output gates
cfharris at erols.com
Sun Apr 9 23:34:29 EDT 2006
Magnus Danielson wrote:
> From: "Robert Lutwak" <Lutwak at Alum.mit.edu>
> Subject: Re: [time-nuts] More on paralleling output gates
> Date: Sun, 9 Apr 2006 16:04:49 -0400
> Message-ID: <001401c65c10$db4f3070$6400a8c0 at lutwakhome>
>> I suspect you're just measuring the bandwidth of your 400 MHz oscilloscope.
> He is close... tau of 1.1 ns should be expected from a 400 MHz.
> I am sitting here and thinking "Hey, isn't those 3 x 50 Ohm sources in parallel
> a impedance missmatch?". If you have a sufficiently long system (> 1/12 of the
> risetime in cable-length which in this case would mean maybe 50 cm or so) we
> must consider it as an impedance system and thus we should care less about the
> bulk capacitance behaviour (which can be "cured" with a stronger source) but
> rather with the source and load impedances relative the cable impedance.
> I'd like to view the exercise as only mildly interesting. Better to find a
> better source for that signal. If you feel like toying around more on that '04
> then directly parallel the outputs into a single 47 Ohm resistor might be more
Which would be exactly the same as putting 150 ohm resistors in series with
each of the three outputs, and tying them all together in parallel.
Which will produce a pulse that is 1/2 height when terminated with 50 ohms...
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