A Fully Symmetric High-Performance Transformer Balun Based on TSV for RF Applications

In this letter, a fully symmetric high-performance 3-D transformer balun based on through-silicon via (TSV) technology is proposed, to improve in-band balance response (phase and amplitude balance). The results show that the operating frequency of the transformer balun is 67.1–81.2 GHz. The insertion loss is less than 1.3 dB with a return loss greater than 10 dB, and magnitude and phase balance are within 0.25 dB and 2.5°, respectively. Vertical interconnection of TSV technology in high-resistance silicon enables the size of the balun to be only $0.32\times0.28$ mm2 ( $0.076\times 0.062\lambda _{g}^{2}$ ).