Linearization conditions for two and four stage circuit topologies including third order nonlinearities

Recently, a novel set of simple conditions were presented for canceling third order nonlinearity in a two-stage amplifier topology. In the present work, detailed linearization conditions are developed for a four-stage topology, expanding upon a prior brief outline of the method. The proposed four-stage topology offers potential advantages in integrated circuit implementation of feedforward linearization, where bulky passive couplers can be replaced by well-matched active circuits. Although the primary focus is on elimination of third order nonlinearities, the approach is readily extended to other order nonlinearities and alternative circuit topologies. In the development, linearization conditions are derived in terms of the gains, intercept points, and coupling coefficients of the devices. The approach provides a more straightforward treatment than more common polynomial-based analysis. In essence, the present methods take a spectral viewpoint, where nonlinear components generated in the frequency spectrum are considered throughout the system and cancelled at the final output. For the two-stage and four-stage topologies, an uncomplicated set of linearization conditions are provided in terms of device characteristics.