A Variable Gain Low-Noise Amplifier for Use in an In tegra ted Television Tuner

The prohibitive cost and size of traditional television tuners are preventing the spread of television to poorer areas and mobile applications. Fully integrated television tuners could reduce the size and cost but currently face issues with noise and linearity which are both strongly dependant on the corresponding specifications of the lownoise amplifier (LNA). Noise and linearity face a trade-off in the LNA which can be dynamically adjusted depending on the input signal level. In this thesis, a variable gain common-source amplifier is proposed to function as the front-end LNA in a television receiver system-on-chip (SoC). The amplifier employs bias asjustment in order to effect a continuously variable gain which the post-layout simulation results show to range from 9.4 dB to 14.5 dB. Noise figure ranges from 4 dB to 2.6 dB over this gain range while IIP3 ranges from 1.8 dBm to 8 dBm. Measurements that correlate well to simulations have not been succesfully made. Unfortunately, the proposed variable-gain common-source LNA employing resistive feedback input matching does not meet the requirements determined by a system study. The system specifications are likely overly ambitious to be feasible with the current technology. Nevertheless, a charge-sampling architecture and corresponding low-noise transconductance amplifier is suggested to meet the system requirements.