An Accurate Automatic Quality-Factor Tuning Scheme for Second-Order <emphasis emphasistype="italic">LC</emphasis> Filters

Abstract

Abstract-This paper presents a scheme to accurately tune the quality factor of second-order LC bandpass filters. The information of the magnitude response at the center and one of the cutoff frequencies is used to tune both the amplitude and the quality factor of the filter using two independent yet interacting loops. Furthermore, the synergic interaction between the loops makes the proposed scheme stable and insensitive to the mismatch between the input amplitudes. A chip prototype was implemented in a 0.35-m CMOS process and consumes 4.3 mA from a single 1.3-V supply. Measurement results show that at 1.97 GHz the quality factor is tunable from 60 to 220 while the amplitude is tunable between 15 and 0 dBm with worst case quality factor and amplitude tuning accuracies of 10% and 7%, respectively.

Process and Temperature Compensation for RF Low-Noise Amplifiers and Mixers

“…Temperature variations are compensated using temperature-independent biasing circuits that provide a nearly constant voltage, current or transconductance within the specified temperature range [2], [3]. The compensation of process variations in RF and analog integrated circuits (ICs) usually requires trimming [4], calibration and/or self-tuning [5]- [8]. Recently, some techniques have been proposed for generating bias currents with a constant value that is independent of temperature and process [9], [10].…”