A 0.5-V Ultra-Low-Power Low-Pass Filter with a Bulk-Feedback Technique

Ultra-low power signal conditioning system for effective biopotential signal recording

“…These signals are acquired by using suitable sensing electrodes before being fed into a biopotential signal conditioning system [12][13][14]. Amplifier and filter circuits have been extensively used by the research community to analyze motor functions of brain as well as cardio signals for treatment of brain and heart related chronic diseases [11,[15][16][17][18][19][20][21][22].…”

“…Based on the literature survey, it has been well understood that the biopotential amplifier and low pass filter (LPF) majorly contribute to power consumption of SoC [1,9,19,20,23]. In this context, a lot of effort is being put in to design a low-power (⩽10 µW) biopotential amplifier along with high DC-gain (⩾40 dB), low input referred noise (1−4 µVrms) and smaller chip area (<1 cm 2 ) [10].…”

“…In this context, a lot of effort is being put in to design a low-power (⩽10 µW) biopotential amplifier along with high DC-gain (⩾40 dB), low input referred noise (1−4 µVrms) and smaller chip area (<1 cm 2 ) [10]. Besides this, researchers have also dedicated their efforts in implementing a low power (<1 µW) filter circuit independent of process voltage and temperature (PVT) variations capable of achieving sharp cut-off frequency (200 Hz), high dynamic range (>45 dB) and low noise (<150 µVrms) [19,20]. However, designing an ultra-low power amplifier circuit with low values of noise and a filter circuit with negligible dependency on PVT is the major challenge being faced by the research community in this field.…”

“…On the other hand, a lot of research work has been done to design an LPF for achieving sharp cut-off frequency and removing out of band noise. Several researchers have proposed various topologies of filter circuits such as g m -C filter [29][30][31][32], active-RC filter [33], complementary source-follower (SF-C) [20] and operational tranconductance amplifier (OTA)-C [32] for biopotential signal recording.…”

“…However, active-RC filter consumes larger area [34], OTA-C filter suffers from high power dissipation as well as high noise values [20,31], and SF-C filter shows high dependency on PVT variations [30]. In an attempt to overcome these challenges Povoa et al [35] reported Tow-Thomas based biquard filter which shows gain of 7 dB with cut-off frequency (fc) of 15 Hz, power consumption of 0.55 µW from 0.9 supply voltage targeted for biomedical applications.…”