Using differences to avoid non-linearity is a pretty common technique used across EE, especially circuit design. Transistors are very non-linear and circuits li

Using differences to avoid non-linearity is a pretty common technique used across EE, especially circuit design. Transistors are very non-linear and circuits like amplifiers have problematic squared terms. However, they're almost always built "differentially": there are both positive and negative input terminals, and positive and negative output terminals. The difference of the output voltages is an amplified version of the difference of the input voltages. Because the squared term at each terminal is the same polarity, subtracting them cancels it out very well. In practice, you're limited by how well the positive and negative paths match, and the mismatch allows some second order term to leak out. Unfortunately, this does not help with the third order terms. See: https://en.wikipedia.org/wiki/Differential_amplifier https://en.wikipedia.org/wiki/Differential_amplifier https://en.wikipedia.org/wiki/Third-order_intercept_point https://en.wikipedia.org/wiki/Third-order_intercept_point