1 Electronics & Signal Processing, Department of Electrical Engineering, Technical University of Denmark2 Department of Electrical Engineering, Technical University of Denmark
This work presents several key aspects in the design of RF integrated circuits for portable multimedia devices. One chapter is dedicated to the application of negative-feedback topologies to receiver frontends. A novel feedback technique suitable for common multiplier-based mixers is described, and it is applied to a broad-band dual-loop receiver architecture in order to boost the linearity performances of the stage. A simplified noise- and linearity analysis of the circuit is derived, and a comparison is provided with a more traditional dual-loop topology (a broad-band stage based on shunt-series feedback), showing a difference in compression point in the order of 10dBm for the same power consumption. The same principle is also applied to a more conventional narrow-band stage in which a single loop is employed in order to enhance noise performances. Noise analysis shows sensible improvements in the noise figure (up to ~1dB) in low-performance technologies, when stringent specifications are considered in terms of power consumption. A recently-reported current-reuse technique, applied to a complete RX frontend, is examined in the following chapter in order to sketch a simplified numerical analysis for the performances of the stage. Semi-ideal models are used in simulations to validate the derived calculations, and the fundamental limits of the basic structure are discussed. The design of a current-mode base-band output stage implemented in a 0.13um technology is presented: the amplifier draws ~500uA from a 1.2V supply, providing 35dB gain and 135MHz GBWP. The integration of high-performance passive components is studied in the last chapter which presents the first reported toroidal inductor fabricated in a standard CMOS process. Field-confinement properties of the structure are exploited in order to reduce the impact of substrate-induced currents. Basic models are derived in the design phase, and the technological limits of the device are considered. Measurement results show that a very compact coil can provide ~1nH inductance up to 20GHz (physical limit for the measurement equipment), with a peak quality factor around 10 at 15GHz.