Publication: Research › Ph.D. thesis – Annual report year: 2007
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.
|Publication date||Jan 2007|
- integrated, RF, CMOS, analogue, circuits
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