Cmos Digital Tv Tuner Realization Of Calibration Technology

With the popularization of Digital Television (DTV), DTV receiver is applied widely around the world. Different TV standards being formulated in many countries and regions make multi-mode multi-standard DTV receiver become a research topic. Filter in multi-mode DTV tuner is studied in this thesis, solving the problems of bandwidth and gain adjusting and frequency tuning.Firstly, origins of variations in CMOS technology, including process variation, systematic variation and random variation, are concluded. The influence of temperature and aging on devices is presented. In terms of the device mismatch, several methods of optimizing mismatch are analyzed.Secondly, fundamental principles and regular implementations of filter are reviewed. To satisfy the requirements of DTV receiver which bandwidth and gain are adjustable, a sixth order elliptic Active-RC LPF with programmable cut-off frequency and gain is presented. And the cascade connection of biquads is discussed, including pole-zero pairing, biquad cascade sequence and gain distribution.Finally, a frequency tuning circuit is proposed for calibrating the frequency shift of filter caused by process and temperature variations. The tuning circuit is also used for calibrating the reference current shift. The design considerations during realization of the circuit are discussed.The results are given:the maximum variation of untuned cut-off frequency and reference current is36%and3.1%respectively, when process corner is FF; the variation of the tuned ones is less than1%and1.9%.