dual pulse generator

We'll have a blast of light that's modulated by a mach-zehnder thing. We want real dark some times so we'll run that modulated light through another e/o modulator driven as a gate. Envision lots of dollars.

We need two gate pulses, programmable in about a 40 ns window. This should work:

We have the parts in stock. At first I thought that using xor gates was dumb, but it's actually cool. The comparator outputs are basically a thermometer code.

The dual comparators can have a little crosstalk between halves, maybe bad to make very short pulses, but we can use the comparators in any order, just by programming the quad 16-bit DAC. I can make two pulses by firing A-C-B-D or anything.

I can set two DACs to +4 volts and take two of the comparators out of the game, to make one pulse if the customer wants to do that. This circuit can make no pulses too!

Crazy simple compared to some other ideas. I was consider using PECL wired-OR to do some combining logic, but that's very nasty with picosecond edges, and every trace a transmission line.