Electronically Tunable Current-Mode Third-Order Square-Root-Domain Filter Design

In this study, electronically-tunable, current-mode, square-root-domain, third-order low-pass filter is proposed. The study is carried out with three circuit designs. First circuit is third-order low-pass Butterworth filter, second circuit is third-order low-pass Chebyshev filter and the last circuit is third-order low-pass elliptic filter. All the input and output values of the filter circuit are current. Only grounded capacitors and MOSFETs are required in order to realize the filter circuit. Additionally, natural frequency f0 of the current-mode filter can be adjusted electronically using outer current sources. To validate the theory and to demonstrate the performance of third-order filter, frequency and time domain simulations of PSPICE program are used. To that end, TSMC 0.35μm Level 3 CMOS process parameters are utilized to realize the simulations of the filter. © 2018 World Scientific Publishing Company

Realization of second-order differential type class-AB log-domain universal filter without changing circuit configuration

In this paper, a new current-mode second-order differential type class-AB log-domain universal filter is proposed. The design is based on the state-space synthesis method. It has simple differential type class-AB structure and using minimum components. The proposed filter has one input and five outputs and can simultaneously realize lowpass (LP), highpass (HP), bandpass (BP), notch (N), and allpass (AP) responses without any changes in the circuit topology. The natural frequency, and the quality factor of the filter can be electronically tuned by changing external currents. Only NPN transistors and grounded capacitors were used, and operated with single power supply of 2 V. PSPICE simulations are given to confirm the theoretical analysis. ©2008 IEEE

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

In this paper, current-mode second-order square-rootdomain 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 statespace 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 μm Level 3 CMOS process parameters