An Edge-Coupled Marchand Balun With Partial Ground for Excellent Balance in 0.13 μm SiGe Technology

• Published in: IEEE transactions on circuits and systems. II, Express briefs Vol. 68; no. 1; pp. 226 - 230
• Main Authors: Chakraborty, Sudipta, Milner, Leigh E., Zhu, Xi, Sevimli, Oya, Parker, Anthony E., Heimlich, Michael C.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: balance; Baluns; Bandwidth; CMOS; Couplings; Ground plane; Impedance; Insertion loss; Marchand balun; SiGe; Silicon germanides; Silicon germanium; Solids
• ISSN: 1549-7747; 1558-3791
• DOI: 10.1109/TCSII.2020.3004642

An edge-coupled meandered three-coupled-line Marchand balun with a partial ground plane implemented in 0.13 μm SiGe Bi-CMOS technology is presented in this brief. The balance performance of the designed balun is significantly improved by creating a `no ground plane' beneath the coupledline structure, which is demonstrated by simulating two baluns: one with a partial ground and the other with a solid ground underneath. The measured amplitude and phase imbalances are less than 0.4 dB and 2.5°, across the 3-dB bandwidth from 21.5 to 95 GHz, surpassing previously reported results of edge-coupled Marchand baluns. The balun occupies 230 μm × 370 μm.