Baroque BJT Digital Driver Stage

Time to upgrade to GaN fets!

I'm just finishing up the rev B layout. The rev A has sub-ns edges, but there's some ringing (around 700 MHz) so I added an absorptive output lowpass filter to beautify the pulse, but that cost me rise/fall time. I'm optimistic that rev B will ring less, or at least at a higher frequency.

Pleasingly symmetric, and exactly 7 PNP and 7 NPN.

piglet

I like the Xerox Alto-like vertical screen of that scope, is there an advantage to using those early digital scopes in 2019? The built in delay-lines probably make it more useful

The display is magnetically deflected, vertical raster scan. The video generator is a couple square feet of TTL. There's a color version, shadow mask tube, but I like my b+w, which is a lot sharper.

They are cheap and work very well. We have at least a dozen 1180x scopes and maybe 50 sampling heads, up to 40 GHz, and TDR, all for about the cost of our one 7 GHz LeCroy (which hardly anyone can remember how to use.)

A non-sampling (realtime ADC) version of my scope might cost a megabuck.

I rarely use the delay-line "internal" trigger. I generally use one of our digital delay generators to manage an experiment, and give the scope a pre-trigger. Or sometimes give the scope a delayed trigger. Our DDGs have much less jitter for longish delays than those scopes do.

A hobbyist or startup could get into the picosecond business with one of these and a few other bits of gear for under $2K.

An interesting box would host a few SD-series Tek sampling heads, with a timebase and a USB interface. Tek showed such a box once at a trade show, but never offered it for sale.