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In this paper, a new current-mode (CM) all-pass filter employing two Dual-Output Second-Generation Current Conveyors (DO–CCIIs), one grounded resistor and one grounded capacitor is presented. The proposed circuit exhibits low input impedance and high output impedance, which makes it suitable for cascading. Moreover, adding two extra resistors to the proposed circuit, a new gain-variable voltage-mode (VM) all-pass filter is obtained. A quadrature oscillator employing minimum number of grounded passive components is derived from the developed CM filter as an application of the first-order all-pass filter. Both of the proposed all-pass filters do not require matching of passive components. The effects of the parasitic impedances of the DO–CCIIs on the transfer function (TF) of the proposed CM filter as an example are investigated. In addition, the proposed CM all-pass filter and oscillator circuit are simulated using SPICE simulation program to confirm the theory.

In this paper, a CMOS current controlled current differencing buffered amplifier (C-CDBA) realization is presented. Also, a new first-order all-pass filter that compensates for some C-CDBA non-idealities is given as an application example. The all-pass filter circuit has low output impedance for easy cascadability and it can be made electronically tunable using the proposed C-CDBA implementation. The theoretical results are verified with SPICE simulations.

In this paper, a novel first-order current-mode (CM) electronically tunable all-pass filter including one grounded capacitor and two dual-output current followers (DO-CFs) is presented. The used DO-CFs are implemented using only 10 MOS transistors granting the proposed CM all-pass filter extremely simple structure. The proposed filter is suitable for integrated circuit (IC) fabrication because it employs only a grounded capacitor and is free from passive component matching conditions. Interestingly the introduced configuration uses minimum number of components compared to other works. It also offers other interesting advantages such as, alleviating all disadvantages associated with the use of resistors, easy cascadability and satisfies all technology requirements such as small sizing, simple realization, low voltage and low power operation. Additionally, the circuit parameters can be easily set by adjusting control voltages. Most favorably, the proposed CM all-pass filter can be simply used as a voltage-mode (VM) all-pass filter with outstanding properties of adjustable gain and tunability. To further show the versatility of the proposed structure a sinusoidal oscillator is also derived from presented CM all-pass filter. Nonideal gain and parasitic impedance effects on developed CM filter are discussed. Finally, simulation results with SPICE program are included to confirm the theory.

In this paper, a new first-order current-mode (CM) universal filter employing two dual output second-generation current conveyors (DO-CCIIs), one resistor and a grounded capacitor is proposed. The proposed filter has low input and high output impedances; thus, it can be easily connected with other CM circuits. It can simultaneously realize first-order low-pass (LP) and all-pass (AP) responses and can provide high-pass (HP) response with interconnection of LP and AP responses. It can be tuned electronically by replacing with dual output second-generation current controlled conveyors (DO-CCCIIs) instead of DO-CCIIs and removing the resistor. It has only a resistor but no capacitor connected in series to X terminal of DO-CCII; accordingly, it can be operated at high frequencies. Also, it does not need any critical passive component matching conditions and cancellation constraints. A number of simulation results based on SPICE program are included to exhibit performance, workability and effectiveness of the proposed filter configuration.

This paper introduces a current-mode first-order all-pass filter (APF) and its application in quadrature oscillator (QO) based on CCCII. The proposed filter can provide inverting and noninverting all-pass functions with a same circuit topology, it uses two CCCIIs and one grounded capacitor. Moreover, the first-order all-pass filter was applied in current-mode sinusoidal quadrature oscillators with the design based on block diagrams. The introduced oscillators can provide four phase-quadrature signals which independently control the condition of oscillation (CO) and frequency of oscillation (FO). The proposed oscillators consist of three CCCIIs and two grounded capacitors. The proposed APF and QOs have high output impedance which can directly drive load without additional current buffer. In addition, they use only grounded capacitors which are very appropriate to future development into an integrated circuit. The results of PSPICE simulation program correspond to the theoretical analysis.

In this paper, a new realization of a current-mode first-order all-pass filter (APF) using a single active building block (ABB) and one grounded capacitor is presented. As the ABB, the current backward transconductance amplifier (CBTA) is used, which is one of the most recently reported active elements in the literature. The theoretical results are in detail verified by numerous SPICE simulations using a new low-voltage implementation of CBTA. In the design, the PTM 90nm level-7 CMOS process BSIM3v3 parameters with $\pm$0.45V supply voltages were used. The proposed resistorless CBTA-C APF provides easy electronic tuning of the pole frequency in the frequency range from 763kHz to 17.6MHz, which is more than one decade. Maximum power dissipation of the circuit is 828$\mu$W at bias current 233$\mu$A. Nonideal, parasitic effects, sensitivity analyses, temperature and noise variation, current swing capability, and Monte Carlo analysis results are also provided. Compared to prior state-of-the-art works, the proposed CBTA-C APF has achieved the highest figure of Merit value, which proves its superior performance.

A new filter operating in voltage mode and realizing all-pass function is proposed. The circuit requires a single current conveyor with an extra voltage input buffer stage and a floating capacitor, enjoys electronic tuning, needs input interface for easy connection and benefits by low output impedance, hence is load-insensitive and operable at twice the frequency range in comparison to other related circuits. In-depth theoretical and simulation studies are presented in support of the newly designed circuit.

A current-mode first-order filter configuration simultaneously providing noninverting and inverting low-pass (LP) and high-pass (HP) responses depending on passive element choice is proposed. In addition, all-pass filter (APF) responses can be easily obtained with interconnection of LP and HP output currents. The proposed filter employs only two differential voltage current conveyors, a grounded resistor and a grounded capacitor, so it is suitable for integrated circuit realization. It provides the feature of high output impedance. It does not need any passive element matching constraints. A voltage-mode oscillator based on the inverting APF is presented as a typical application. The performance of the proposed configuration is verified through many SPICE simulation and experimental test results.

In this paper, two new first-order voltage-mode all-pass filters (APFs) are proposed. Each of the proposed APFs comprises a single modified DDCC-, and has high input impedance. The first and second APFs can provide first-order noninverting and inverting APF responses, respectively. As passive elements, the first APF comprises two grounded capacitors, and a floating resistor while the second one uses a grounded resistor, a floating resistor and a grounded capacitor. However, both of the APFs suffer from a matching problem. Two quadrature oscillators (QOs) obtained from the APFs are presented. Simulations of the APF and QO circuits are fulfilled via the SPICE program. Besides, diverse experiments for the APFs are made to verify the performances.

In this paper, a novel complementary metal-oxide semiconductor (CMOS) transistors based first-order voltage-mode all-pass filter is proposed. The filter circuit employs six metal-oxide semiconductor (MOS) transistors and minimal number of passive components, i.e., a resistor and a capacitor. The core of the proposed filter is a CMOS inverting amplifier with unity gain. The proposed circuit exhibits some attractive features such as compact design, high input impedance and ability to provide non-inverting and inverting all-pass responses simultaneously. Additionally, it does not require any kind of passive element matching constraints. Furthermore, by replacing the passive resistor with an active negative channel metal-oxide semiconductor (NMOS) transistor, the proposed filter is enriched with the much-desired feature of tunability. The theoretical behavior is tested and demonstrated by carrying SPICE simulations using TSMC 0.18$\mu$m level-7 CMOS process parameters.

A new universal active filter configuration is presented in this paper which is capable of realizing all three first-order filter responses namely all pass (AP), low pass (LP) and high pass (HP) using a single second generation voltage conveyor (VCII+), a virtually grounded capacitor and two resistors. The proposed circuit offers tunability of the cut-off frequency, gain (for HP filter) and simultaneous availability of two filter outputs, one at a low impedance node (HP/AP), the other output, namely the LPF will require a voltage buffer to avoid loading. The nonideal analysis of filter responses based on the nonideal model of VCII+ is carried out by considering all the parasitic immittances and nonideal gains and found that they have no significant effect on the performance of the proposed filter structure. Sensitivity analysis with respect to active and passive components has also been carried out. The functionality of the presented circuit has been validated through simulations and experimental results, where the VCII+ was implemented using the macro model of the commercially available CFOA IC AD844. Additionally, the proposed circuit has been tested using a CMOS VCII+ implemented with 0.18$\mu$m TSMC technology parameters. The tests include advanced evaluations based on Monte Carlo simulations.