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This paper presents a single current difference transconductance amplifier (CDTA) based all-pass current mode filter. The proposed configuration makes use of a grounded capacitor which makes it suitable for IC implementation. Its input impedance is low and output impedance is high, hence suitable for cascading. The circuit does not use any matching constraint. The nonideality analysis of the circuit is also given. Two applications, namely, a quadrature oscillator and a high

In filter applications pertaining to voice or audio frequency range, the magnitude characteristics play important role due to insensitivity of ear to change in phase whereas the phase characteristics dominate in video signal transmission. All pass filters are widely used for shifting the phase of the input signal while keeping the amplitude constant over the desired range of frequency. All-pass filters have also been used in the realization of dual element frequency controlled oscillator with certain benefits in harmonic rejection and quadrature property [

The main intention of this paper is to present a current mode first order all-pass filter configuration based on CDTA [

The circuit symbol of ZC-CDTA is shown in Figure

Circuit symbol of ZC-CDTA.

ZC-CDTA implementation.

The proposed first order all-pass filter based on ZC-CDTA is shown in Figure

Proposed current mode all-pass filter.

The frequency performance of the filter circuit may deviate from the ideal one due to nonidealities. The nonidealities effect may be categorized in two groups: parasitics and transfer errors. The equivalent circuit of CDTA in presence of nonidealities may be represented as shown in Figure

ZC-CDTA with nonidealities.

In this section, two applications of the proposed APF have been presented.

The all-pass filter of Figure

Proposed quadrature oscillator.

A high

Proposed band pass filter.

It may be noted that the value of

To validate the theoretical analysis, the circuit of Figure

Magnitude and phase response of the proposed current mode all-pass filter.

Transient response of the filter with sinusoidal input at 1.35 MHz.

Relation between magnitudes of input and output.

To demonstrate the functionality of quadrature oscillator, an oscillator is designed for 1.35 MHz frequency. The various component values are

Quadrature current outputs of the proposed oscillator topology.

The band pass filter is designed for 135 KHz frequency with the 100 pF capacitor and bias currents _{03}. The simulated results are shown in Figure

Magnitude plot of proposed band pass filter.

A new CM first order all-pass filter configuration based on a single CDTA and one grounded capacitor has been presented in this paper. The topology is suitable for cascading as it possesses low input and high output impedances. It possesses attractive feature of electronic tunability of pole frequency and phase characteristics. Two applications are developed namely a quadrature oscillator and a high