Chun-Li Hou

Quadrature oscillators using CCIIs

Three third-order quadrature oscillators are proposed. Outputs of two sinusoids with 90° phase difference are available in each quadrature oscillator circuit. The oscillation condition and oscillation frequency of each proposed quadrature oscillator are orthogonal controllable. All proposed circuits employ only grounded capacitors. The use of only grounded capacitors is ideal for integration. Experimental results are included to confirm the theoretical analysis.

Current-mode and voltage-mode universal biquads using a single current-feedback amplifier

A new current-mode universal biquad and a new voltage-mode universal biquad using a single current-feedback amplifier are proposed in this paper. Both biquads enjoy the following advantages: realization of highpass, bandpass and lowpass filtering from each configuration, avoidance of input voltage tracking error in a current-feedback amplilfier; only one active component; no requirement for match components; low passive and active sensitivities. An inverting amplifier is used to form a notch filter. Experimental results are obtained to prove the theoretical analyses.

Voltage-mode universal biquadratic filters with one input and five outputs using MOCCIIs

Two new voltage-mode universal biquadratic filters each with one input terminal and five output terminals are presented. The first proposed circuit uses three multiple output second-generation current conveyors (MOCCIIs), two grounded capacitors and six resistors. The second proposed circuit employs four MOCCIIs, two grounded capacitors and seven resistors. Each of the proposed circuits can realize all the standard filter functions; highpass, bandpass, lowpass, notch and allpass, simultaneously, without changing the passive elements. The proposed circuits enjoy the features of orthogonal controllable of resonance angular frequencies and quality factors, using only grounded capacitors as well as low active and passive sensitivities.

Analytical synthesis of high-order single-ended-input OTA-grounded C all-pass and band-reject filter structures

The synthesis method based on the analytical solution of a single nth-order filter transfer function and the generation of n+1 simple and realizable transfer functions implemented using lossless integrators and one additional constraint is applied to facilitate the development of new voltage-mode high-order operational transconductance amplifiers and capacitors (OTA-C) all-pass and band-reject filters. The presented nth-order all-pass and band-reject filters contain n+2, i.e., at least n fewer OTAs and enjoy lower component spread than the recently published filter structures in addition to achieving three criteria: all single-ended-input OTAs, all grounded capacitors, and the least number of component counts, simultaneously. Furthermore, two different types of the synthesized filter structures, equal capacitance and equal transconductance, are suggested for easier IC manufacture and simpler biasing architecture, respectively. H-Spice simulations, using 0.25-mum process and plusmn1.25-V supply voltages, validate theoretical predictions

Novel universal current-mode filters using unity-gain cells

Two novel universal current-mode filters using unity-gain current followers (CFs) and voltage followers (VFs) are presented. The first one, employing three CFs, one VF, two grounded capacitors and two resistors, has two inputs and three outputs. The second one, employing only two CFs, one VF, two grounded capacitors and two resistors, has four inputs and a single output. Both proposed circuits oOEer the following advantageous features: universal current-mode filter realization from the same configuration, no requirements of component matching conditions, employment of two grounded capacitors ideal for integration, employment of two virtually grounded resistors good for voltage control, easy adjustment of ω0/Q and ω0 through separate virtually grounded resistors and low active and passive sensitivity performance.

Universal active filter using four OTAs and one CCII

Abstract A new universal active current filter with a single input and three outputs using only four operational transconductance amplifiers (OTAs), one second-generation current conveyor ( CC11) and three grounded capacitors is presented. In addition to the OTAs and CCII, only capacitors are required as passive devices. The grounded capacitors make the network ideal for integration.

Current-Mode Universal Biquadratic Filter with Five Inputs and Two Outputs Using Two Multi-Output CCIIs

A current-mode universal biquadratic filter with five input terminals and two output terminals is presented. The proposed circuit uses two multi-output second generation current conveyors, two grounded capacitors and three resistors. The new circuit offers the following advantages: use of the minimum number of active components, orthogonal controllability of resonance angular frequency and quality factor, use of grounded capacitors and the versatility to synthesize any type of active filter transfer functions.

Cascadable Current-Mode First-Order and Second-Order Multifunction Filters Employing Grounded Capacitors

A configuration for realizing low input and high output impedances current-mode multifunction filters using multiple output second-generation current conveyors (MOCCIIs) is presented. From the proposed circuit configuration, first-order allpass, highpass, lowpass and second-order allpass, notch, bandpass filters can be obtained. The simulation results confirm the theoretical analysis.

Multi-input differential current conveyor, CMOS realisation and application

The adjoint circuit of a multiple output second-generation current conveyor (MOCCII) is investigated. It is found that the adjoint circuit of MOCCII is an multi-input differential current conveyor (MIDCC). A CMOS realisation of the MIDCC with three plus-type input terminals and two minus-type input terminals is described. As an example of applying the MIDCC, the transforming of a current-mode filter using MOCCIIs to its adjoint voltage-mode filter using MIDCCs is discussed.

Voltage/Current-Mode Multifunction Filters Using One Current Feedback Amplifier and Grounded Capacitors

One configuration for realizing voltage-mode multifunction filters and another configuration for realizing current-mode multifunction filters using current feedback amplifiers (CFAs) are presented. The proposed voltage-mode circuit exhibit simultaneously lowpass and bandpass filters. The proposed current-mode circuit exhibit simultaneously lowpass, bandpass and highpass filters. The proposed circuits offer the following features: no requirements for component matching conditions; low active and passive sensitivities; employing only grounded capacitors and the ability to obtain multifunction filters from the same circuit configuration.