Power and area efficient MOSFET-C filter for very low frequency applications
New circuit design techniques for implementing very high-valued resistors are presented, significantly improving power and area efficiency of analog front-end signal processing in ultra-low power biomedical systems. Ranging in value from few hundreds of MX to few hundreds of GX, the proposed floating resistors occupy a very small area, and produce accurately tunable characteristics. Using this approach, a low-pass MOSFET-C filter with tunable cutoff frequency (f(C) = 20 Hz-184 kHz) has been implemented in a conventional 0.18 mu m CMOS technology. Occupying 0.045 mm(2)/pole, the power consumption of this filter is 540 pW/Hz/pole with a measured IMFDR of 70 dB.
mosfet-c filter cmos integrated circuits continuous-time filter high-valued resistance low-power programmable filter subthreshold weak inversion widely tunable circuits