Q-enhancement of a low-power gm-C bandpass filter for closed-loop sensor readout applications

In this paper, a Q-enhancement technique for gm-C biquadratic bandpass filters is discussed. The frequencies of the parasitic pole-zero pair of a low-transconductance OTA are altered with an additional compensation capacitor, which cancels the nonidealities of the resonator. The presented technique...

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Bibliographic Details
Main Authors: De Dorigo, Daniel, Rombach, Stefan, Maurer, Michael, Marx, Maximilian, Nessler, Sebastian, Manoli, Yiannos
Format: Conference Proceeding
Language:English
Subjects:
bandpass
Bandwidth
Capacitors
Circuit stability
gm-C
low power
Q-factor
Resonant frequency
sensor readout
Stability analysis
Tuning
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Summary:In this paper, a Q-enhancement technique for gm-C biquadratic bandpass filters is discussed. The frequencies of the parasitic pole-zero pair of a low-transconductance OTA are altered with an additional compensation capacitor, which cancels the nonidealities of the resonator. The presented technique is used to design a resonator which fulfills the requirements on a loop-filter for closed-loop delta-sigma sensor readout applications. The high stability of the Q-factor against transconductance and center frequency tuning, as well as against process variations is discussed and demonstrated with transistor-level simulations. The designed resonator exhibits a 3-sigma worst-case Q-factor larger than 3600 at the nominal center frequency of 25 kHz and a Q-factor larger than 1000 over the tuning range from 13 kHz to 32 kHz.
ISSN:0271-4302
2158-1525
DOI:10.1109/ISCAS.2015.7168724