| RF front ends are a very highly researched topic in the world of wireless communications. Research is focused in this area because the front end is arguably the most vital component in making a communication system function properly. The front end has three functions. The first is to amplify or attenuate the RF input signal to provide a constant amplitude output to the analog to digital converter (ADC). Second, it must provide programmable channel selection by means of a phase-locked loop (PLL). And third, to prevent aliasing in the ADC, it must also low-pass filter the base-band output. The main building blocks which compose the front end are: the variable-gain amplifier (VGA); Mixer; PLL; and low-pass filter. The primary goal of this thesis is to design and simulate a VGA in all CMOS technology for use in a satellite TV tuner. Previous solutions for VGA's in this application have used more expensive and less integrated Silicon Bipolar or GaAs technologies. Therefore, the benefit to completing this design in all CMOS is to reduce cost and to improve overall tuner integration. The design and simulations will be accomplished using a 0.35mum CMOS technology and there are a number of specifications which the VGA design must meet including Matching, Noise Figure (NF), Linearity (IIP3), Input Return Loss (IRL), and Dynamic Range. |
