Re: Fast monostable with a transistpor array

On Fri, 14 Jun 2024 09:03:03 -0700, john larkin <jl@650pot.com> wrote:

On Fri, 14 Jun 2024 11:08:56 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
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"john larkin" <jl@650pot.com> wrote in message news:hilo6j9dgctalpiu4v09rpdavf6fetm1cv@4ax.com...

On Thu, 13 Jun 2024 23:25:37 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
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"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:v4f2nm$2augj$1@dont-email.me...

One option John Larjkin doesn't seem to have explored is using Renesas HFA3096 five transistor array as basis for his
mononstable
and level shifter.
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It offers three 8GHz NPN parts and two 5.5GHz PNP parts in a single array.
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https://www.renesas.com/us/en/document/dst/hfa3046-hfa3096-hfa3127-hfa3128-datasheet?r=494216
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I put the NPN model parameters into a circuit designed by yourself.
It's late now but I got as far as Time step too small.
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That is neither fast nor a monostable.

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Yes ok it's an astable and certainly not intended to be fast.
It was intended only to see if the model worked. Nothing more.

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It doesn't work!
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There's no reason to use many-GHz parts in micropower circuits. One
reason is that the sim breaks.

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Most versions of the HFA3046 are obsolete. The only one left at
Digikey costs $12. It would be risky to design around that part.
Wasn't  HFA originally a Harris part?
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There are lots of dual (non-monolithic) diodes and bipolars and fets
around, but the monolithic arrays are mostly gone.
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The duals save space, but aren't well matched so are electrically and
thermally equivalent to buying two separate parts.
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I wonder if one could design really fast stuff with the HFA3046.
Package parasitics look nasty. And the big package will force ugly PCB
routing. You can plop a single tiny transistor wherever you want.
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The HFA parts are either 5 NPNs or 5 PNPs, which is also awkward.
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The original simulation of the astable multivibrator was intended
to demonstrate reasonable speed at low power.

The model was published by Intersil in 1996 in app note MM3046.

The simulation runs if properly typeset.

RL