High-Q above-IC inductors using thin-film wafer-level packaging technology demonstrated on 90-nm RF-CMOS 5-GHz VCO and 24-GHz LNA

High-Q inductors are important for the realization of high-performance, low-power RF-circuits. In this paper, on-chip inductors with Q-factors above 40 have been realized above the passivation of a 90-nm RF-CMOS process using wafer-level packaging (WLP) techniques [1]. The influence of a patterned polysilicon and metal ground shield on the inductor-Q is compared and the influence of highly doped active area underneath the inductors is shown. A 5-15 GHz above-IC balun has been realized on 20 Ω · cm silicon with the use of patterned ground shield. The technology is demonstrated by a low-power 90-nm RF-CMOS 5-GHz VCO with a core current consumption of only 150 μA with a 1.2-V supply, and a 10% tuning range with a worst case phase noise of - 111 dBc/Hz at 1-MHz offset. A 24-GHz single-stage common-source low-noise amplifier has been realized, with a noise figure of 3.2 dB, a gain of 7.5 dB, and a low power consumption of10.6 mW.