The
transformer balun comprises a first
metal layer, a second
metal layer, a third
metal layer, a primary coil and a secondary coil, the first metal layer, the second metal layer and the third metal layer are sequentially arranged from the bottommost end to the topmost end, the primary coil is arranged on the second metal layer, and the secondary coil is arranged on the third metal layer; an
inductor is connected in series with a
capacitor to be connected to a
center tap of the primary coil to form a power supply path, a
choke inductor of the power supply path is arranged on the first metal layer, and the
capacitor is an adjustable
capacitor; a first connecting through hole is formed between the first metal layer and the second metal layer, and a
choke inductor of the power supply path is connected with the primary coil based on the first connecting through hole; a second connecting through hole is formed between the second metal layer and the third metal layer, and the grounding end of the secondary coil is grounded based on the second connecting through hole; according to the invention, the common-mode
signal can be effectively absorbed at all frequency points, the
broadband performance of the
balun is optimized, the CMRR and balance degree of the
balun are improved, and the high-frequency power is also optimized.