J
John Larkin
Guest
On Thu, 20 May 2004 10:14:02 -0700, Jim Thompson
<thegreatone@example.com> wrote:
Yeah. This is an NMR gradient amp. It has to make up to 10 amp pulses
into an inductive load, with noise and pulse flatness below 5 PPM,
zero offset below 0.2 PPM. All sorts of bizarre things start to matter
down there.
Even the picosecond stuff cares about minute power supply ripples,
thermals, ground loops, stuff like that if you want to keep the jitter
comparable to the other specs.
In Jim Williams' first Analog Design book, there's a cool horror story
(chapter 26) about noise problems in a failed frequency synthesizer
project. Everybody who does electronics should be required to read his
two books.
John
<thegreatone@example.com> wrote:
On Thu, 20 May 2004 10:05:49 -0700, John Larkin
jjlarkin@highSNIPlandTHIStechPLEASEnology.com> wrote:
On 20 May 2004 09:33:12 -0700, Winfield Hill
Winfield_member@newsguy.com> wrote:
John Larkin wrote...
I'm trying to figure out how to put a 200 ps, 200 volt
gaussian pulse into 2 ohms. Got any advice?
A 2ps 200V pulse into 2 ohms? That's easy, use ohms law.
Make a 100A 2ps gaussian pulse and you'll be all set.
That was 200 ps Win. Even I'm not crazy enough to try for 2!
We might go for 400 volts into 8 ohms, and use a tapered line, but
that's kinda bulky for the gadget we have in mind. A shock line would
be fun, but most diodes are fully depleted at pretty low voltages.
But today, I'm still working on this 30 KHz amplifier...
John
Isn't it funny? A number of my most difficult designs have been at
low or moderately low frequencies.
...Jim Thompson
Yeah. This is an NMR gradient amp. It has to make up to 10 amp pulses
into an inductive load, with noise and pulse flatness below 5 PPM,
zero offset below 0.2 PPM. All sorts of bizarre things start to matter
down there.
Even the picosecond stuff cares about minute power supply ripples,
thermals, ground loops, stuff like that if you want to keep the jitter
comparable to the other specs.
In Jim Williams' first Analog Design book, there's a cool horror story
(chapter 26) about noise problems in a failed frequency synthesizer
project. Everybody who does electronics should be required to read his
two books.
John