Hal Murray wrote: >> Every time I dig through the 5370 schematics, I think to myself >> "wouldn't it be nifty to build a replacement plug-in card with a >> modern fast CPU to run the instrument", but I try and stop myself >> there. >> > > Suppose you start with an FPGA on a PCI card. > > What sort of front end would you want? What can you build with home/hacker > technology? > > My straw man is something to turn a digital signal out of a comparator into a > ramp that gets feed into an A/D clocked on the system's internal clock. The > ramp needs to be a little over a cycle wide. > > Anybody got a circuit to make a linear ramp? > > Hal
Current mode ramp generators using long tailed pairs to switch the charging current for a capacitor are the time honoured approach for fast ramp generators. This technique is still used today in IC designs with a mosfet used to discharge the capacitor rather than the more traditional Schottky diode pair. NIST used a similar technique for the interpolators in their multichannel frequency measurement setup which monitors the stability of several standards against GPS. Bruce _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
