Measuring propagation delay of 4000 logic family chips

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Discussion Overview

The discussion revolves around methods for measuring the propagation delay of 4000 logic family chips, focusing on whether a circuit can be built using logic gates to achieve this measurement. Participants explore the feasibility and safety of creating oscillating circuits to demonstrate propagation delay.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about simple methods to measure propagation delay using logic gates and expresses concern about the safety of creating an oscillating circuit.
  • Another participant suggests using a signal generator and oscilloscope as a standard method, but acknowledges the interest in alternate methods like a ring oscillator.
  • There is a concern about whether the propagation delay is low enough to potentially damage the chip when creating an oscillating circuit.
  • One participant reassures that forming a ring oscillator does not damage the gates and is a common technique in electrical engineering.
  • Another participant notes that using a single inverter would not result in oscillation without additional components, such as a crystal.

Areas of Agreement / Disagreement

Participants express differing views on the safety and feasibility of using logic gates to measure propagation delay through oscillation. While some suggest it is safe, others raise concerns about potential damage to the chips.

Contextual Notes

Participants do not reach a consensus on the best method for measuring propagation delay or the safety of the proposed oscillating circuit. There are also unresolved assumptions regarding the specific conditions under which the chips may be damaged.

Bipolarity
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Is there a simple way I can measure the propagation delay of my logic gates? For instance, is there a circuit I can build (using logic gates) to measure the propagation delay?

What if I tried building a circuit whose output constantly oscillates? This would certainly prove that the propagation delay is very low, but is this a good idea? Will my chip/battery die? Any expert opinions?

BiP
 
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Bipolarity said:
Is there a simple way I can measure the propagation delay of my logic gates? For instance, is there a circuit I can build (using logic gates) to measure the propagation delay?

What if I tried building a circuit whose output constantly oscillates? This would certainly prove that the propagation delay is very low, but is this a good idea? Will my chip/battery die? Any expert opinions?

BiP

Normally you measure it using a signal generator and an oscilloscope. Are you looking for alternate ways to measure the prop delay?

If so, google "ring oscillator"...
 
berkeman said:
Normally you measure it using a signal generator and an oscilloscope. Are you looking for alternate ways to measure the prop delay?

If so, google "ring oscillator"...

Yes, I'm trying to measure it with logic gates alone. Well not a precise measurement (not looking for specific numbers). I am basically trying to create an experiment to show the circuit oscillating rapidly. I am just worried that the propagation delay is so low that it will damage my chip. Is it safe to create an oscillating circuit using chips manufactured in the 4000 family? Will my chip explode?

For instance, suppose I created the circuit Y = Y'. Certainly the output would constantly oscillate. But enough to damage my circuit?

BiP
 
Bipolarity said:
Yes, I'm trying to measure it with logic gates alone. Well not a precise measurement (not looking for specific numbers). I am basically trying to create an experiment to show the circuit oscillating rapidly. I am just worried that the propagation delay is so low that it will damage my chip. Is it safe to create an oscillating circuit using chips manufactured in the 4000 family? Will my chip explode?

For instance, suppose I created the circuit Y = Y'. Certainly the output would constantly oscillate. But enough to damage my circuit?

BiP

Did you do the Google search that I suggested? That is the typical gate-based way to measure prop delay.

If you try doing it with just one inverter, the input and output voltages will settle to about Vcc/2 and stay there static. No oscillation unless you stick a crystal between the input and output of the inverter.

And no, forming a ring oscillator does not damage the gates. That is a standard part of an EE's "toolbox" of useful circuits.
 
Last edited:
Thanks!

BiP
 

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