^{1}

^{*}

^{2}

^{*}

^{1}

^{*}

^{3}

^{*}

This realization of a voltage-mode first order voltage-mode all pass filter (VM-APF) employing single current differencing differential input transconductance amplifier (CDDITA) as active component is presented. The proposed configuration employs one CDDITA along with two resistors and one grounded capacitor. The pole frequency and phase shift of proposed VM-APF are electronically tunable by transconductance of CDDITA. The proposed circuit is verified by SPICE simulations.

An first order all-pass filter is one of the most important building block of many analog signal generation/pro- cessing applications. It is frequently used for phase shifting purpose while maintaining the amplitude of signal constant over the desired range of frequency. It finds applications in realizing high selectivity active bandpass filters, delay equalizers and quadrature oscillators [

Therefore, the aim of this paper is to propose a new voltage-mode all-pass with following advantageous features: i) Single ABB realization; ii) use of only two resistors; iii) use of only one capacitor; iv) use of grounded capacitor which is desirable from the viewpoint of monolithic integration and v) electronically tunable phase and pole frequency.

The CDDITA is one of the recent active ABB which have been introduced in [

The proposed voltage-mode first order all-pass filter (VM-APF) is shown in

The routine circuit analysis of proposed VM-APS shown in

for

From Equation (1) it is clear that voltage gain is unity. The pole frequency and phase response obtained from Equation (1) are

and

So, proposed circuit provides phase shift from 0 to 180˚. The pole frequency is electronically tunable by transconductance g_{m}.

The circuit illustrated in _{1} = IB_{2} = IB_{3} = 100 µA and with the transistor model parameters of PR100 N(PNP) and NR100 N(NPN) of the bipolar arrays ALA400 from AT&T [_{1} = R_{2} = 500 Ω. The frequency and phase responses of proposed VM-APF are shown in

A new voltage-mode first-order all-pass filter employing single CDDITA, two resistors and one grounded capacitor is presented. The positive features of proposed circuit are use of single ABB, use of grounded capacitor and availability of electronic tuning feature. The theoretical analysis is verified by SPICE simulations.

Dinesh Prasad,Kuldeep Panwar,D. R. Bhaskar,Mayank Srivastava, (2015) CDDITA-Based Voltage-Mode First Order All Pass Filter Configuration. Circuits and Systems,06,252-256. doi: 10.4236/cs.2015.611025