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Does anyone know what the digital circuit symbol which looks like a triangle with an arrow through it means?

It's in a circuit for pulse shrinking. I assume its just a delay. Can anyone confirm or deny my hunch?

enter image description here

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  • \$\begingroup\$ \$A_{SH}\$ probably means the signal A SHifted (or delayed) but this is just a guess. \$\endgroup\$
    – Syed
    Dec 22, 2021 at 4:18

2 Answers 2

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A diagonal arrow through a symbol generally refers to some aspect of that element being adjustable (usually but not always by a mechanical knob or slider). You can see this in the symbols for a variable capacitor, variable inductor, rheostat (variable resistor), and sometimes you even see it on voltage and current source symbols to represent a variable source.

Since this is an arrow through a buffer, I would assume it refers to a buffer with some aspect of it being variable. Unlike all the other examples given above, though, a buffer doesn't usually have any values specified on the schematic that one might vary--so the arrow must refer to one of the parameters that isn't usually specified, and the only one of those that I can think of that would make any sense in context is the propagation delay. So I'd guess, purely on the symbol, that this refers to a variable delay.

Looking at the diagram given, it does appear to have the function of delaying a signal, since A' is shown to be a delayed and inverted version of A, and A' is just A after an inverter and the mystery block. It seems they're using it to create an edge detector (which they call a "pulse-shrinking circuit") consisting of an inverter, the variable delay block, and an and gate, which they then feed two copies of into another and gate to create a coincidence detector.

Note that the fact that it's a variable delay is something I have no evidence of other than the arrow on the symbol. So I could be wrong. Something about that delay block is adjustable, though.

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I haven't seen that symbol before, but from the text, it apparently represents their "pulse shrinking circuit" - I would use a monostable multivibrator ("one-shot") to implement that function.

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