CML-CML level shifter

John Larkin · 2021-12-24T22:21:18+00:00

I have a differential output from a fast CML flipflop, powered by +3and ground, and want to drive another CML-input part. If the loadgadget was also powered from +3, I'd just connect them with a coupleof 50 ohm traces. But the Vcc of the destination part could beanything from +3 to -2. I want full speed and DC coupling, so the ideal part to put in serieswith both runs is a battery of the appropriate voltage, namely thedifference in supply voltages. Couldn't find anything that would worklike that.This thing below sorta fakes the batteries. It seems to work. Theconstraints on the CML transmitter (how far can the pins actuallyswing?) and on the receiver device (how far can the pins actuallyswing?) are far from clear, so we'll have to test this some.This looks pretty simple, but took a lot of thinking and many stupidsimulations to get it to be simple. It bothered me enough to keep atit. Can't ski... too much snow.Version 4SHEET 1 2664 1128WIRE 48 32 -144 32WIRE 128 32 48 32WIRE 320 32 288 32WIRE 352 32 320 32WIRE 544 32 496 32WIRE 576 32 544 32WIRE 848 32 736 32WIRE 944 32 848 32WIRE 1328 32 1296 32WIRE 1360 32 1328 32WIRE 1664 32 1632 32WIRE 1696 32 1664 32WIRE -144 80 -144 32WIRE 944 80 944 32WIRE 1296 80 1296 32WIRE 1632 80 1632 32WIRE 128 144 128 32WIRE 288 144 288 32WIRE 496 144 496 32WIRE 736 144 736 32WIRE 1296 192 1296 160WIRE 1632 192 1632 160WIRE -144 224 -144 160WIRE 944 224 944 160WIRE -32 368 -144 368WIRE 128 368 128 224WIRE 128 368 48 368WIRE 224 368 128 368WIRE 288 368 288 224WIRE 288 368 224 368WIRE 352 368 288 368WIRE 496 368 496 224WIRE 496 368 416 368WIRE 608 368 496 368WIRE 736 368 736 224WIRE 736 368 608 368WIRE 1328 416 1296 416WIRE 1360 416 1328 416WIRE 1664 416 1632 416WIRE 1696 416 1664 416WIRE -144 448 -144 368WIRE 1296 464 1296 416WIRE 1632 464 1632 416WIRE 1216 480 1200 480WIRE 1264 480 1216 480WIRE 1600 480 1488 480WIRE 1376 496 1328 496WIRE 1392 496 1376 496WIRE 1712 496 1664 496WIRE 1728 496 1712 496WIRE 1264 512 1152 512WIRE 1488 512 1488...