When it comes to learning digital system design, hobbyists and students have a lot of options, whether it’s tinkering with field-programmable gate arrays or working up chip submission for a Tiny Tapeout run. But similar tools for analog design have been harder to come by. Certainly you can create analog circuits in a simulator like LTspice and test them against theory. But nothing beats building real analog circuits and measuring their actual, not theoretical, behavior. Measurement is complicated for analog designs because the test equipment can affect the very measurement being made.

To address this educational gap, a team led by me at Columbia University’s department of electrical engineering created MOSbius, a breadboard-friendly chip that you can think of as a field-programmable transistor array for analog designs.

As its name suggests, MOSbius is built around metal-oxide-semiconductor transistors, divided between n-type and p-type transistors. As these are the building blocks of most analog integrated circuits today, designing with the MOSbius provides experience that’s directly relevant to creating real chips.

The MOSbius has 68 pins, of which 63 connect to either individual transistors or common analog subcircuits such as current mirrors and op-amp stages. Two other pins are used for positive and negative supply voltages.