Nonlinear Shaping SC Oscillator With Enhanced Linearity

Sang Wook Park, JosÉ L. Ausin, Faramarz Bahmani, Edgar Sanchez-Sinencio
2007 IEEE Journal of Solid-State Circuits  
A nonlinear shaping technique for a switched-capacitor (SC) bandpass filter (BPF) based oscillator yielding enhanced linearity is presented. Usually, for an SC oscillator consisting of a BPF and a two-level comparator, the linearity can only be improved by increasing the quality factor (Q-factor) of the BPF. This paper proposes an efficient way to improve the linearity of SC BPFbased oscillators. In particular, by replacing the conventional twolevel comparator by a sound multilevel comparator,
more » ... ilevel comparator, a nonlinear shaping of the signal at the output of the comparator causes a significant improvement in linearity. To illustrate the effectiveness of the proposed technique, one conventional SC BPF-based oscillator and the proposed oscillator have been designed and fabricated in a standard 0.35-m CMOS technology. Each oscillator was designed to operate from a 1.65 V supply voltage and a master clock frequency of 80 MHz. The oscillation frequency is 10 MHz and the Q-factor of the BPF is 10. Experimental results demonstrate that the proposed scheme improves the third-order harmonic distortion by 20 dB with respect to the conventional SC BPF-based oscillator.
doi:10.1109/jssc.2007.907167 fatcat:ha7lfvarqrfhtc3pzbuklbdp3a