Design and characterization of symmetric multi-tap transformers

Symmetric multi-tap transformers are designed, modeled, and characterized. Simple mathematical calculations are utilized to estimate the inductances and coupling coefficients from the physical parameters of a multi-tap transformer, which reduces the time required to develop an initial design. A broadband lumped-element model is then presented and its accuracy is demonstrated by comparing the extracted inductances from the model to Momentum simulation results. A concentric and an interleaved symmetric multi-tap transformer are designed in 0.13μm CMOS RF process and their self-inductances, coupling coefficients, and quality factors are evaluated.