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biasing 74HC14 input to 1/2 VCC for small signals

You pretty much have it, except the timing is a little different so that no overlap charge loses occur.

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
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Reply to
Jim Thompson
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That's what I figured. Femtofarads and total liberty in device geometries , something us board level designers can't do. But we have to mind lurkers who see this and don't realize it was for a chip design where Id is under designer control.

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Regards, Joerg

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Joerg
[snip]

Sequence of events:

Close SW2 Close SW3 Open SW3 Open SW2 Close SW1 Observe "OUT" Open SW1 | Repeat

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

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| 1962 | I love to cook with wine Sometimes I even put it in the food

Reply to
Jim Thompson

True, all 'AC were not created equal--mine was a preproduction sample. Several parts burned themselves up. I notified the vendor--Fairchild, I think--and the production parts seemed better.

Too late though--I'd already designed in an 'HC part instead.

It was for a single-stage x7 frequency multiplier, the first such AFAIK, and it saved the company. I see Paul Burridge talking about the fine points in sed circa 2004, so I s'pose now it's common knowledge.

But back to yours, your 'AC00 is driven continuously with a pretty large signal. It doesn't spend much time being linear, so it wouldn't get as hot.

Cheers, James Arthur

Reply to
James Arthur

Agreed. A proper comparator is the way to go. I recall I considered to use an HC14 as a comparator but after digging up some specs from different manufacturors it appeared the hysteresis isn't well defined.

Electronic parts are like people: it is very odd to find a typical (conforming to normal) one.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
                     "If it doesn\'t fit, use a bigger hammer!"
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Reply to
Nico Coesel

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