Design of third-order square-root-domain filters using state-space synthesis method

In this study, square-root-domain electronically tunable, third order low-pass filter is proposed. First circuit is third-order low-pass Butterworth filter and second circuit is third-order low-pass Chebyshev filter. Additionally, the cut-off frequency of the proposed filters can be electronically tuned by changing external currents. Time and frequency domain simulations are performed using PSPICE program for third order filters to verify the theory and to show the performance of them. For this purpose, the filters are simulated by using TSMC 0.35 μm Level 3 CMOS process parameters.