7400 competition entry: Using two CD4007 IC as an op amp to generate sine waves

Here’s an interesting way of designing analog devices using digital chips. This sine wave generator¬†s based around¬†mosfets contained in the CD4007 IC (a dual complementary pair of mosfets and an inverter).

The CD4007 dual complementary pair and inverter is primarily intended for digital logic circuits. It contains an inverter, and two pair of PMOS and NMOS transistors that can be configured to implement any CMOS logic gates. Since we now have access to pairs of transistors, it should be okay to use these transistors for other purposes than digital, in other words: analog. This idea is not new, in fact this article has already mentioned this possibilty, and now I would like to take the challenge to build something somewhat useful out of it, as simple as possible…

Build something that uses or abuses a logic chip and get amazing boards, tools, and other swag. The Open 7400 Logic Competition promotes awareness of the basic building blocks of modern circuits. Devious geeks ignited the computer revolution with discrete logic computers, what can you do? Details and entry form here.

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