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3.6‐8.1 GHz CMOS balun with 1.8° in‐band phase difference by using capacitive balance compensation technique
Author(s) -
Yang Geliang,
Tang Kai,
Wang Zhigong
Publication year - 2020
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.32228
Subject(s) - balun , insertion loss , capacitor , cmos , materials science , capacitive sensing , electrical engineering , phase (matter) , return loss , wideband , transmission line , optoelectronics , physics , engineering , voltage , quantum mechanics , antenna (radio)
In this letter, a passive ultra‐wideband balun with high balance performance is proposed. The balun is realized by using a pair of planar spiral coupled transmission lines and a capacitor which is responsible for the capacitive balance compensation. The straight‐forward scattering matrix derivation shows that the proposed structure can achieve full output balances both in amplitude and phase. For demonstration, two baluns with and without the compensating capacitor were designed and fabricated in a 65‐nm complementary metal‐oxide‐semiconductor (CMOS) process. The measured results show that the compensated balun features a measured insertion loss ≤5.2 dB and a return loss ≥10 dB from 3.6 to 8.1 GHz. Within such a wide frequency range, the measured amplitude and phase difference are ≤0.2 dB and 1.8°, respectively, which are much better than its uncompensated counterpart.