Symmetric Planar and Stacked Millimeter-wave Transformers Using a Single Thick Metal

In this paper, planar and stacked transformers with enhanced symmetry across both primary and secondary are proposed for mm-wave applications. A 0.13 μm BiCMOS technology using a single thick metal is used for comparison. Trade-offs involving symmetry and insertion loss (IL) of the transformer are demonstrated using silicon measurements upto 50 GHz. Measurements show 8.6 % (0.944 - 1.026) and 13.3% (1.162 - 1.317) increase in IL at 28 GHz for planar and stacked configurations, respectively while achieving enhanced symmetry.