Novel current-mode second-order square-root-domain highpass and allpass filter

In this paper, current-mode second-order square-root-domain highpass, and allpass filters are proposed by using only a circuit. Literature survey showed that, current-mode second-order highpass and allpass filters are not proposed. The proposed circuit is derived from first-order blocks. The presented of the first-order blocks are based on the state-space synthesis method with two subcircuit; square-root and squarer/divider circuits. The proposed circuit has one input and one output and can realize highpass (HP), and allpass (AP) responses without any changes in the circuit topology. Only MOS transistors and grounded capacitors are required to realize the filter circuit. The center frequency of the filters can be electronically tuned by changing external currents. Time and frequency domain simulations are performed using PSPICE program for the filters to verify the theory and to show the performance of them. For this purpose, the filter is simulated by using TSMC 0.35 ¿m Level 3 CMOS process parameters.