On Tue, 23 Sep 2008 08:33:04 -0700, Jim Thompson
wrote:


On Tue, 23 Sep 2008 08:18:58 -0700, John Larkin
wrote:

On Tue, 23 Sep 2008 08:07:40 -0700, Jim Thompson
wrote:


I need to convert a _slow_ moving analog signal to "1" or "0",
depending on whether it is above or below the digital threshold
(CMOS).

Problem: If I go directly into a gate or D-input of a flop I can get
substantial overlap current rail-to-rail.

This is a very low current application.

Any suggestions?

...Jim Thompson

What's the technology... discrete or inside an IC?

Inside an IC, I'm designing it.


How low is "low current"

1uA


Speed/hysteresis requirements?

I have ~10us to make a decision, no hysteresis (yet).


What's the input signal level?


John


0V-to-3.3V CMOS levels, out of a _very_ slow comparator.

...Jim Thompson


How about a couple of common-base (or common-gate) stages. Input goes
to emitters; PNP base is maybe 1 volt below Vcc; NPN base is +1 from
ground, both base drives weak if it's bipolars, anything for fets.
Collectors/drains connected together are the output.


John