The Realization of Current-Mode Electronically Tunable Square-Root Domain Low-pass Filter Based on CMOS Technology for Biomedical Applications

In this study, a second-order low-pass filter with low-power and voltage, current mode and square-root domain was designed for biomedical implementations at low frequencies using the state-space-synthesis method. The filter, which is activated at 3V supply voltage, is formed using current mirrors, current-mode square-root circuits, and grounded capacitors. To indicate the performance of the filter, some simulations are carried out using process parameters of TSMC 0.25µm CMOS in the program of ORCAD Capture CIS. The results of these simulations show that the center frequency of low-pass filter can be tuned electronically between the range of 1 kHz and 120 kHz and that there appears to be a 0.5% total harmonic distortion. The proposed circuit has some advantages, such as activating at low-frequency operation, low power supply, tunability, and low total harmonic distortion.