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likephysics
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Why is the CMOS logic voltage exactly 3.3V, why not 3V or 3.5V?
Fish4Fun said:"Logic Families" (http://en.wikipedia.org/wiki/Logic_family) are typically built for compatibility and involve "standards". A particular family generally employs identical silicon level transistors to perform a wide range of functions. Designing a die component requires considerable engineering, so it makes sense to reuse them.
A "new" generation is typically designed with specific goals in mind, including, but not limited, to backward compatibility, lower power consumption, faster response time, higher bandwidth and smaller die area. In most cases 3.3V logic can interface with 5V logic, but consumes less power, is faster and has a smaller die. 3.3V is certainly not the lowest voltage CMOS logic family, 2.5V and 1.7V logic are quite common in high density, high-speed ICs like RAM and Processors.
I hope that helps answer your OP.
Fish
By lowering the power supply from 5V to 3.3V, switching power was reduced by almost 60 percent (power dissipation is proportional to the square of the supply voltage).
CMOS voltage refers to the voltage levels used in complementary metal-oxide-semiconductor (CMOS) circuits. These circuits are commonly used in electronic devices, and the most common voltage levels used are 3.3V, 5V, and 12V.
3.3V is a commonly used voltage in CMOS circuits because it strikes a good balance between power consumption and performance. It is also compatible with most modern electronic devices and components.
CMOS voltage is directly related to logic levels, as it determines the threshold for high and low logic states. In a 3.3V CMOS circuit, any voltage above 2.0V is considered a high logic state, while any voltage below 0.8V is considered a low logic state.
Yes, CMOS voltage can affect the speed of a circuit. Generally, a higher voltage can result in faster switching times and therefore improve the speed of a circuit. However, this also means higher power consumption and potential heat dissipation issues.
One potential downside of using 3.3V CMOS voltage is that it may not provide enough noise immunity for certain applications. In these cases, a higher voltage, such as 5V, may be required. Additionally, 3.3V circuits may be more sensitive to fluctuations in power supply, which can affect their performance.