Widely tunable low‐pass <i> g _m </i>  −  <i>C</i> 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.