High-accuracy and low signal distortion on-chip auto-calibrating architecture for continuous-time filters

Design and implementation of analog tracking filter for ac signal acquisition

“…They are typically embedded in the generic ac signal acquisition circuit shown in Figure 1 to reduce measurement noise and improve the signal-to-noise ratio (SNR) of the channel. [2][3][4] In many studies about tunable BPFs, active RC filters, Gm-C filters, and switched-capacitor (SC) filters are frequently used, where phase-locked techniques, [5][6][7][8][9] SC techniques, [10][11][12][13] digital control techniques, [14][15][16][17] or other tuning techniques [18][19][20][21][22] are introduced to tune the center frequency, quality factor, and bandwidth of the filter. A self-tuning biquad BPF is designed based on the Gm-C filter topology with a phase-locked loop, which is robust to parameter perturbations through automatic tuning and can also be used as a selective amplifier.…”

“…A second‐order SC BPF is implemented for Internet‐of‐Things applications, where the center frequency of the filter can be tuned between 3.9 and 7.1 kHz by changing the clock's frequency 11 . A fourth‐order RC BPF is designed for use in GNSS receivers, and it is digitally controlled to achieve a frequency tuning range of ±30% with a tuning error of less than 5% 14 . A low‐power second‐order BPF is designed based on the switched‐resistor technique for neural recording applications, and the filter exhibits a tuning range of the resonance frequency from 200 to 400 Hz 19 …”

“…11 A fourth-order RC BPF is designed for use in GNSS receivers, and it is digitally controlled to achieve a frequency tuning range of ±30% with a tuning error of less than 5%. 14 A low-power second-order BPF is designed based on the switchedresistor technique for neural recording applications, and the filter exhibits a tuning range of the resonance frequency from 200 to 400 Hz. 19 These works show excellent frequency tuning methods.…”