Widely tunable low‐pass g m − C filter for biomedical applications

Abstract

This study presents a fourth-order, low-pass Butterworth transconductor–capacitor filter with tunable bandwidth for biomedical signal processing front-ends. An architecture has been proposed for realising very low transconductance values with tunability. This transconductor architecture makes it possible to realise a fully differential filter without the need for explicit common-mode feedback circuit. The filter has two tuning schemes, a resistor-based tuning ( R -tuning) and a switched transconductor-based tuning ( D -tuning). With R -tuning, the bandwidth is adjustable between 1 and 70 Hz and with D -tuning, the tuning range is 30 mHz–100 Hz. The filter has been designed in united microelectronics corporation (UMC) 0.18 µm complementary metal–oxide–semiconductor process. In terms of figure-of-merit, the proposed filter is found to be on par with the filters reported in the literature.