Practical realization of electronically adjustable universal filter using commercially available IC-based VBDA

This paper describes the practical realization of electronically adjustable voltage-mode universal filter with three inputs and single output (TISO) using the commercially available integrated circuit (IC)-based voltage differencing buffered amplifiers (VDBAs). The realization is resistor-less and contains only two VDBAs and two capacitors. The described filter structure can realize all the five standard biquadratic filter functions from the same configuration without needing any component matching criterions. It also exhibits low-output impedance, which enables for easy cascading in voltage-mode operation. Owing to practical VDBA realization, the filter circuit can be easily made electronically tunable with orthogonal o-Q tuning. The effects of the VDBA non-idealities on the filter performance have been analyzed in detail. To prove the theoretical finding, the performance of the studied circuit was also experimentally measured using the operational transconductance amplifie

Dual-mode multifunction filter realized with a single voltage differencing gain amplifier (VDGA)

This article presents the dual-mode multifunction biquad filter realized employing only a single voltage differencing gain amplifier (VDGA), one resistor and three capacitors. The proposed filterwith one input and three outputs can configure as voltage-mode or current-mode filter circuit with the appropriate input injection choice. It can also synthesis the three standard filter functions, which are highpass, bandpass, and lowpass responses without modifying the circuit configuration. Orthogonal adjustment between the natural angular frequency (o) and the quality factor (Q) of the filter is achieved. Detail analysis of non-ideal VDGA effects and circuit component sensitivity are included. The circuit principle is verified by means of simulation results with TSMC 0.35-m CMOS process parameters

Electronically Tunable Phase Shifter Using CDTAs

The realization of an electronically tunable phase shifter using current differencing transconductance amplifiers (CDTAs) as active components is presented. The proposed filter employs only two CDTAs and one virtually grounded capacitor, which its phase shift can be electronically adjusted by varying the bias current of the CDTA. The circuit also exhibits high-output impedance, which is easy cascading in the current-mode operation. As application example, the current-mode biquad filter based on the proposed CDTA-based phase shifter circuit is also presented. PSPICE simulation results of the proposed circuit and its application are given to confirm the theoretical analysis.APSIPA ASC 2009: Asia-Pacific Signal and Information Processing Association, 2009 Annual Summit and Conference. 4-7 October 2009. Sapporo, Japan. Poster session: Advanced Circuits and Systems/VLSI (5 October 2009)

Current tunable current-mode biquadratic filter using dual-output current followers

This paper describes a current-mode multifunction filter with a minimum number of active and passive elements using dual-output current followers (DO-CFs) as active elements. By based on the dual-output current-controlled current conveyor (DO-CCCII)-based current followers, the proposed filter consists of only two DO-CFs and two grounded capacitor, without an external passive resistor requirement. The filter can realize all the standard biquadratic functions without changing the circuit configuration. Moreover, its natural angular frequency and bandwidth is controllable independently and electronically by adjusting an external bias current, and its active and passive sensitivities are low.APSIPA ASC 2009: Asia-Pacific Signal and Information Processing Association, 2009 Annual Summit and Conference. 4-7 October 2009. Sapporo, Japan. Poster session: Advanced Circuits and Systems/VLSI (5 October 2009)

Universal voltage-mode SIFO-type biquad with fully MOS-C realization using DDCCTAs

516-522An electronically tunable universal voltage-mode biquad filter which is based on using the newly introduced active building block, namely differential difference current conveyor transconductance amplifier (DDCCTA) is presented in the present paper. The proposed circuit having single input and five output (SIFO) terminals uses two DDCCTAs, two grounded capacitors and two electronic resistors suitable for MOS-C realization. The circuit realizes all the five standard biquadratic filter functions simultaneously without changing circuit topology. In addition, the circuit features the high-input impedance terminal, an electronic control of its natural angular frequency and quality factor. The workability of the proposed circuit has been verified using PSPICE simulations based on CMOS DDCCTA implemented in 0.5 <span style="font-family:Symbol; mso-ascii-font-family:" times="" new="" roman";mso-hansi-font-family:"times="" roman";="" mso-char-type:symbol;mso-symbol-font-family:symbol"="" lang="EN-GB">mm MIETEC CMOS technology. </span

Current-mode high-Q bandpass filter and mixed-mode quadrature oscillator using ZC-CFTAs and grounded capacitors

600-607<span style="mso-bidi-font-weight: bold" lang="EN-GB">This paper presents the realization of the current-mode bandpass filter and mixed-mode quadrature oscillator both from the same circuit configuration. The proposed circuit is in the resistor-less structure, which contains only four z-copy current follower transconductance amplifiers (ZC-CFTAs) as active components together with two grounded capacitors as passive components. As the first configuration, the current-mode BP filter with high quality factor (Q) is proposed. The center frequency (wo) and the Q of the circuit are orthogonal adjustable via the gm-value of the ZC-CFTA. From the same topology, the mixed-mode quadrature oscillator can easily be realized that is capable of generating two explicit quadrature current outputs and two quadrature voltage outputs, simultaneously. Moreover, the realized oscillator also provides the advantage of orthogonal electronic control of the oscillation condition and oscillation frequency, which makes it suitable as variable frequency oscillator. PSPICE simulation results using bipolar ZC-CFTA have been given to verify the workability of the two proposed circuits. <span style="mso-bidi-font-weight: bold"> </span

Resistorless voltage-mode first-order allpass section using single current-controlled conveyor transconductance amplifier

335-340This paper presents an alternative configuration for realizing a canonical voltage-mode first-order allpass (AP) section with electronic tuning. The proposed circuit is composed of only one CCCTA and one floating capacitor, which results in a simple and resistorless structure. Its phase response can be adjusted electronically through the external dc bias currents of the CCCTA. Simulation results based on 0.35 m BiCMOS process parameters with ± 0.75 V supply voltages are provided to demonstrate the performance of the proposed AP section. </span

CDBA-Based Universal Biquad Filter and Quadrature Oscillator

The voltage-mode universal biquadratic filter and sinusoidal quadrature oscillator based on the use of current differencing buffered amplifiers (CDBAs) as active components have been proposed in this paper. All the proposed configurations employ only two CDBAs and six passive components. The first proposed CDBA-based biquad configuration can realize all the standard types of the biquadratic functions, that is, lowpass, bandpass, highpass, bandstop, and allpass, from the same topology, and can also provide orthogonal tuning of the natural angular frequency (ωo) and the bandwidth (BW) through separate virtually grounded passive components. By slight modification of the first proposed configuration, the new CDBA-based sinusoidal quadrature oscillator is easily obtained. The oscillation condition and the oscillation frequency are independently adjustable by different virtually grounded resistors. The sensitivity analysis of all proposed circuit configurations is shown to be low. PSPICE simulations and experimental results based upon commercially available AD844-type CFAs are included, which confirm the workability of the proposed circuits

Single VDGA-Based Mixed-Mode Universal Filter and Dual-Mode Quadrature Oscillator

This article presents the circuit designs for a mixed-mode universal biquadratic filter and a dual-mode quadrature oscillator, both of which use a single voltage differencing gain amplifier (VDGA), one resistor, and two capacitors. The proposed circuit has the following performance characteristics: (i) simultaneous implementation of standard biquadratic filter functions with three inputs and two outputs in all four possible modes, namely, voltage-mode (VM), current-mode (CM), trans-admittance-mode (TAM), and trans-impedance-mode (TIM); (ii) electronic adjustment of the natural angular frequency and independently single-resistance controllable high-quality factor; (iii) performing a dual-mode quadrature oscillator with simultaneous voltage and current output responses; (iv) orthogonal resistive and/or electronic control of the oscillation condition and frequency; (v) employing all grounded passive components in the quadrature oscillator function; and (vi) simpler topology due to the use of a single VDGA. VDGA non-idealities and parasitic elements are also investigated and analyzed in terms of their influence on circuit performance. To prove the study hypotheses, computer simulations with TSMC 0.18 μm CMOS technology and experimental confirmatory testing with off-the-shelf integrated circuits LM13600 have been performed