This paper presents a technique to improve RF integrated inductor performance, incorporating double ground shield using polysilicon and n+ buried layer, providing a fully shield and preventing the electric field penetration. This method was compared with conventional inductors, patterned ground shield, double ground shielding using polysilicon inductors, and improves Q-factor up to 50% at 3.5, 4 and 5 GHz. The results were obtained based on AMS 0.35μm BiCMOS technology. This technique can be applied to any BiCMOS technology without any additional process. ©2008 IEEE. Capovilla, C.E., Tavora, A.S.A., Kretly, L.C., A fully integrated 2.5GHz band CMOS Low Noise Amplifier with multiple switched inputs for diversity wireless communications (2007) IEEE MTT-S Microwave and Optoelectronic Conference, pp. 625-629. , OctM. Usami, M. Ohki, The p-chip: an ultra small 2.45GHz, RFID chip for ubiquitous recognition applications, IEICE Trans. Electron., e86-c,no.4, pp. 521-528, Apr 2003C. P.Yue, C.Ryu, J.Lau, T. H.Lee, and S. S.Wong, A physical model for planar spiral inductors on silicon, Proc. IEEE Int. Electron Devices Meeting, San Francisco, CA, 1996Craninckx, J., Steyaert, M., A 1.8-GHz Low-Phase- Noise CMOS VCO Using Optimized Hollow Spiral Inductors (1997) IEEE Journal of Solid-State Circuits, 32 (5), pp. 736-744. , MayYue, C.P., Wong, S.S., On-Chip Spiral Inductors with Patterned Ground Shields for Si-Based RF IC's (1997) Symposium on VLSI Circuits, pp. 85-86Sun, Y., van Zejl, Y.H.W., Tauritz, J.L., Baets, R.G.F., Suspended membrane inductors and capacitors for application in silicon MMIC's (1996) IEEE Microwave and Millimetre-Wave Monolithic Circuits Symposium Digest, pp. 99-102. , JunYim, S.-M., Chen, T., O, K.K., The effects of a ground shield on spiral inductors fabricated in a silicon bipolar technology (2000) Proc. Bipolar/BiCMOS Circuits and Technology Meeting (BCTM), pp. 157-160. , SeptE. Ragonese, A. Scuderi, T. and G. Palmisano, Experimental comparison of substrate structures for inductors and transformers, in 12th IEEE Mediterranean Electrotechnical Conference (MELECON 2004), Dubrovnik, Croatia, pp. 143-146, May 2004Ragonese, E., Girlando, G., Palmisano, G., A very accurate design of monolithic inductors in a 2D EM simulator (2002) Proc. IEEE Int. Conf. on Electronics, Circuits and Systems (ICECS 2002), pp. 1199-1202. , Dubrovnik, Croatia, pp, SeptTan, H.P., Ma, J.G., Yeo, K.S., Do, M.A., High-Q Si-Based Inductor Shielded With Double-Layer Polysilicon for RF Applications (2000) Microwave and Optical Technology Letters, 24 (6). , MarchAustriamicrosystems, 0.35 m HBT BiCMOS Process Parameters, , Application Note ENG-219 Rev. 3.0http://www.sonnetusa.com, Sonnet Software Inc. AvailableBurghartz, J.N., Ruehli, A.E., Jenkins, K.A., Soyuer, M., Nguyen-Ngoc, D., Novel substrate contact structure for high-Q silicon-integrated spiral inductors (1997) Tech. Dig. Int. Electron Devices Meeting (IEDM), pp. 55-58Mernyei, F., Darrer, F., Pardoen, M., Sibrai, A., Reducing the Substrate Losses of RF Integrated Inductors (1998) IEEE Microwave and Guided Wave Letts, 8 (9), pp. 300-301