Advantages and Disadvantages of a High Frequency

Thread Starter

David Waddell

Joined Dec 3, 2014
24
Hello

Just looking to know what the main advanagtes and disadvanatages of a high frequency in a circuit. ( 7400 Series and 4000 Series). Just looking for some background information to my assignment.
 

crutschow

Joined Mar 14, 2008
25,130
What's your assignment?
The higher the frequency, the shorter the time to process a specific digital function, with a higher frequency causing the effects noted by MrChips.
Another problem with very high frequencies is that the PCB layout and grounding becomes more critical.
 

Thread Starter

David Waddell

Joined Dec 3, 2014
24
So?

You asked about 7400 series logic and 4000 series logic and you got an answer that did not distinguish between them. Since 4000 series logic IS a CMOS family, why don't you think the answer applies to CMOS?
Because CMOS circuits use less power, so I wanted to confirm that he wasn't talking generally about frequency
 

MrChips

Joined Oct 2, 2009
21,370
74C00 series is CMOS. Also 74HC00 series.

What I said applies to all logic, CMOS and non-CMOS technology.

Have you noticed that as PCs run at faster clock speeds the heat sinks on the CPU are getting bigger. The PCs generate more heat and the fans have to work harder to keep the mother board cool.
 
Last edited:

crutschow

Joined Mar 14, 2008
25,130
7400 TTL logic uses bipolar transistors, takes a lot of static power and that power only goes up slightly with frequency.
74#C#00 and CD4000 series logic are CMOS and take very little static power but the power goes up with frequency since most of the power goes into charging/discharging circuit capacitances and that power is a linear function of frequency.
 
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