0.5 V, Low Power, 1 MHz Low Pass Filter in 0.18 µm CMOS Process

In this paper a low power continuous-time 4th order low pass Butterworth filter operating at power supply of 0.5 V is presented. A 3-dB bandwidth of 1 MHz using technology node of 0.18 μm is achieved. In order to achieve necessary head-room, the filter uses pseudo-differential bulk-driven transconductor. A master-slave based common mode feedback(CMFB) circuit sets the output common mode voltage of transconductor. The simulation results show that the filter has a dynamic range of 54 dB and consumes a total power of 36 μW when operating at a supply voltage of 0.5 V. The Figure of Merit (FOM) achieved by the filter is 0.05 fJ, lowest among similar low-voltage filters found in the literature. The simulation result show that the 3-dB bandwidth variation for process, voltage and temperature is less than ±10%.