Design of an IPD ultra wideband Marchand balun using a phase compensation line

An ultra wideband (UWB) 3.1~10.6 GHz on-chip IPD Marchand balun is presented in this paper. It uses rectangular spiral shaped coupled line to increase coupling coefficient and reduce chip area. Moreover, the bandwidth of phase imbalance is increased by using phase compensation line in order to meet the requirement of UWB band. To demonstrate and validate the proposed method, the UWB Marchand balun was implemented on a high-resistivity (3k Ω-cm) silicon IPD technology. The measurement results show low insertion loss and good performance on amplitude imbalance and phase imbalance. The amplitude imbalance was within ± 0.54 dB and the corresponding phase imbalance was below 5.8^°. The chip size of proposed balun was 1.15 mm².