Re: 7000 test/cal module(s) and backplane breakout board.


Ed Breya
 

Current mirrors should work fine. I presume you meant to say four PNP transistors for the DAC and level shifting from ground referenced and +5V powered TTL/CMOS. I looked at all sorts of schemes back then, and concluded that the DACs were the way to go for my needs. You can get better performance from the current mirror if you use transistor arrays. I think a CA3046 or something in that family has enough NPNs to make two mirrors.

The edges of the TS signals are intentionally very slow, to minimize interference with the sensitive circuitry - do NOT make them go faster. As I recall, the readout system makes its decision on the value either in the middle of the TS, or right at the end, when it begins to turn off. The internal clocking is not precise in frequency (you actually don't want it constant), but the relative timing of each event is exact (all digital).

Ed

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