Abstracl -The impact of the inter-system and the intrasystem isolations on the performance of GPS receivers is analyzed. The grounding, shielding and de-coupling structures were optimized to minimize the level of intrasystem interference in the receiver. By reducing the intrasystem interference, high sensitivity and high immunity to jamming signals were simultaneously achieved. The sensitivity value helow the -14ldBm and CW power level of -4dBm, ZdBm and ZdBm in the DCS1800, IS-95. and WCDMA frequency ranges respectively for 3dB degradation of the carrier to noise ratio were obtained. An overview of the basic positioning technologies for mobile phones for the UTRAN and the GSM networks is presented in [I] and [2] respectively. Hybrid positioning methods and architectures are described in [3]. Refs [4,5] present W related issues, requirements and specifications of GPS for operation in the presence of wireless communication systems.The simultaneous operation of GPS and wireless communication systems (WCS) "d the tight integration required in portable mobile devices impose severe constraints in the GPS receiver design. The performance of the GPS receiver should remain akin to its standalone performance regardless of the proximity of the wireless system. Highly linear low noise GPS receivers, operating at low power consumption levels are required. A49 0-7803-7695-1/03/$17.00 0 2003 IEEE