Double Volterra series approach to FET mixers

Abstract

calculation of parasitic shunt capacitance between the plate and ground plane gives 0.5 pF for the perforation ratio of 56%, that is, around 20% of the main capacitance. The capacitor with a conventional blanket ground has an SRF of 6.83 GHz, f QϾ30 of 6.1 GHz, and C eff of about 3 pF at 3 GHz. Also, the Q factor was around 85 in the 3-GHz range, while the parasitic shunt capacitance was 0.97 pF. The 56% perforation results in a 40% reduction of shunt capacitance, which improves the SRF by 0.8 GHz, f QϾ30 by 1.1 GHz, and Q factor by 224% without change of effective capacitance. Even though there was a slight further improvement of isolation with 44% perforation, the RF performance listed above was seriously degraded, as compared to the 56% case. From the analysis we can conclude that the capacitor cell shielded with 56% perforation ground (600-m square edge and 200-m conductor width) reveals the optimized isolation and RF performance for 3D RF circuit integration. CONCLUSIONThis work reports the design of an isolated capacitor cell of high values of Q factor and SRF for LTCC 3D RF circuit application. The optimized capacitor cell with perforated ground of 600-m square edge and 800-m pitch revealed good isolation of Ϫ20 dB transmission up to 15 GHz from a vertical interferer (located 114-m above) and a lateral interferer (located 300-m away). The fabricated 2.8-pF capacitor revealed an SRF of 7.6 GHz and Q factor of over 190 up to 3 GHz, which is an improvement of SRF by 0.8 GHz and Q factor by 224%, as compared to the conventionally grounded capacitor. ACKNOWLEDGMENTS This work was financially supported in part by the Ministry of Science and Technology of Korea and the Korea Institute of Science and Technology Evaluation and Planning (KISTEP).