Meeting the tough linearity and noise required by GSM and UMTS receivers in CMOS technology is challenging. A new IIP2 calibration technique based on canceling the second order nonlinearities of mixer, generated in the input RF transistors, is introduced. By using this technique about 22 dB mixer IIP2 improvement is achieved. The proposed calibration circuit can be used in multi-standard mixer because of high bandwidth of the calibration circuitry. Moreover it can work with voltage supplies as low as 1 V. Using this technique a multi-standard mixer supporting PCS, UMTS and IEEE802.11b-g is developed. The design is done in CMOS 65 nm technology with 1.2 V supply while it consumes about 7 mA current.

The linearity and noise required by GSM and UMTS receivers make the design of a CMOS mixer for these applications so challenging. A new technique for IP2 improvement in Zero-IF active mixers is presented in this paper. This inductor-less technique is based on canceling the parasitic capacitor of common source node of the switching transistors and synthesizing resistive impedance. Using this technique, a reconfigurable down converter mixer works from 900 MHz to 2.4 GHz is designed supporting GSM, DCS, PCS, UMTS and IEEE802.11 b-g standards. The mixer IIP2 is higher than 71 dBm in GSM and UMTS bands. The mixer conversion gain is higher that 12 dB in all frequency bands. The design is done in 65 nm CMOS technology and consumes 10 mA from a 1.2 V supply. The design meets the performance required for all mentioned standards, while its area and power is comparable with high performance single band mixers.

In future, mobile terminals may be linked in various types of local network where the whole network is moving. Mobile networks will need to provide global connectivity to such moving networks and manage their mobility. A moving network consists of mobile terminals and a mobile router, which acts as the gateway to the mobile network. To manage the mobility of the moving network, it is important to minimize the packet overhead, to optimize routing, and to reduce the volume of handoff signals over the mobile network and air interface. This paper proposes a new routing mechanism using hierarchical mobile network prefix assignment, home agent concatenation, hierarchical address management, and hierarchical re-routing. In hierarchical mobile network prefix assignment, a mobile router is assigned a mobile network prefix, which is used as a prefix when allocating the location addresses of mobile terminals in the moving network, so allowing them to be managed in a hierarchical manner. Home agent concatenation limits the number of home agents which need to be updated during handoff by enabling one home agent hold information relating to others, while hierarchical address management minimizes the volume of handoff signals by managing the location addresses of all mobile terminals in a hierarchical manner. Hierarchical re-routing introduces a local anchor router in order to localize handoff and to optimize routing. Simulation results show that our proposed routing method is better than the conventional solutions in terms of efficiency of data transmission including data transmission delay, and handoff performance.

An even-harmonic mixer using a bipolar differential pair (bipolar harmonic mixer;BHMIX) is theoretically analyzed from the direct conversion point of view; i.e, conversion gain, third-order input intercept point (IIP3), self-mixing induced dc offset level, and second-order input intercept point (IIP2). Also, noise are analyzed based on nonlinear large-signal model, and numerical results are given. Noises are treated as cyclostationary noises, thus all the folding effects are taken into account. Factors determining IIP3, IIP2, dc offset, and noise are identified and estimation procedures for these characteristics are obtained. For example, design guidelines for the optimal noise performance are given. Measured results support all the analysis results, and they are very useful in the practical BHMIX design.