Inverse Bandpass Filter Research Articles

Fourth‐order inverse filter configuration using current differencing buffered amplifier

AbstractThis article presents three different higher‐order inverse filter (IF) configurations using current differencing buffered amplifier (CDBA) as an active component and a few passive elements. The topology can be used to synthesize fourth‐order inverse low pass filter (FO‐ILPF), inverse band pass filter (FO‐IBPF), and inverse all‐pass filter (FO‐IAPF) using suitable admittance combinations. PSPICE simulations verify the functionality of the proposed IFs with the CMOS‐based CDBA using 180 nm technology. The theoretical analysis and simulated results are also carried out, which shows that they are in close agreement. The passive sensitivity analysis, non‐ideality analysis, Monte Carlo simulation, temperature analysis, percentage of total harmonic distortion (%THD), and noise analysis of the proposed filters are also performed. The proposed design has also been implemented using the current feedback operational amplifier (CFOA) as IC AD844AN to verify the functionality.

A New Realization of Third-Order Inverse Bandpass Filter and Its Application as an Oscillator

A new operational transresistance amplifier (OTRA)-based third-order inverse bandpass filter (IBPF) is presented in this paper. To illustrate an application of the presented IBPF, the proposed configuration is used to implement a third-order quadrature oscillator (TOQO). Furthermore, the nonideal behavior of the proposed topologies has been examined using a single-pole model of the OTRA. It is perceived that for high-frequency applications, the effect of nonidealities may be eliminated through self-compensation. Passive sensitivities are computed and are found to be less than half, rendering proposed topologies insensitive to component variations. Phase noise study and frequency stability analysis have been carried out and found that the proposed TOQO enjoys good frequency stability. The proposed circuits’ workability is verified through an Analog Design Environment (ADE) Spectre tool provided by Cadence Virtuoso using 0.18 [Formula: see text]m CMOS gpdk process parameters. Monte Carlo statistical analysis is also carried out to assess the prefabrication performances. Total harmonic distortion (THD) for the proposed IBPF is found to be less than 5%. Pre- and post-layout simulations are also included to affirm the theory. Excellent agreement among simulation results and theory is observed.

Minimal Realization of Fractional-Order Inverse Filters

In this paper, a voltage mode (VM) multifunctional structure of fractional-order inverse filter using a single operational amplifier (op-amp) is proposed. The proposed configuration of inverse filter has been designed using a novel R-C op-amp circuit using minimum number of active and passive components (one op-amp, two resistors and two simulated fractional-order capacitors). The presented structure, by appropriate choice(s) of different passive elements, can realize fractional-order inverse low-pass filter, fractional-order inverse band pass filter and fractional-order inverse high-pass filter. The circuits described are eminently suitable for VM signal processing as they have ideally infinite input impedance. Experimental results using µA741 op-amp, discrete resistors and simulated fractional-order capacitors (α = 0.7) realized using Valsa method, numerical simulations using MATLAB and circuit simulations using PSPICE have been presented to establish the workability of the proposed circuits. The stability and sensitivity analyses have also been presented for the realized fractional-order inverse filters.

CMOS CDBA-Based Inverse Filter Structure

This paper presents a voltage-mode(VM) tunable multifunction inverse filter configuration employing current differencing buffered amplifiers (CDBA). The presented structure utilizes two CDBAs, two/three capacitors and four/five resistors to realize inverse low pass filter (ILPF), inverse high pass filter (IHPF), inverse band pass filter (IBPF), and inverse band reject filter(IBRF) from the same circuit topology by suitable selection(s) of the branch admittances(s). PSPICE simulations have been performed with 0.18μm TSMC CMOS technology to validate the theory. Some sample experimental results have also been provided using off-the-shelf IC AD844 based CDBA.

Multifunction Filter/Inverse Filter Configuration Employing CMOS CDBAs

A voltage-mode (VM) multifunction configuration for the realization of conventional active filters and inverse active filters (IAF) using two current differencing buffered amplifiers and six passive elements has been presented. The proposed structure can realize low pass filter/inverse low pass filter (LPF/ILPF), high pass filter /inverse high pass filter (HPF/IHPF), and band pass filter/ Inverse band pass filter (BPF/IBPF) from the same circuit topology by appropriate choice(s) of the branch impedance(s). PSPICE simulations with CMOS current differencing buffered amplifiers implemented in 0.18μm CMOS TSMC technology have been presented to establish the workability of the proposed circuit configuration.