Maw-Huei Lee

Universal active current filter using two multiple current output OTAs and one CCIII

A new universal active current filter with a single input and three outputs; which uses only two multiple current output operational transconductance amplifiers (OTAs), one third-generation current conveyor (CCIII), and two grounded capacitors is presented. In addition to the OTAs and CCIII, only capacitors are required as passive devices. The grounded capacitors make the network ideal for integration.

New universal biquad filters using only two unity-gain cells

New current-mode and voltage-mode universal biquad filters are presented using only two unity-gain cells (one current follower and one voltage follower) in each configuration. The proposed filters employ one less follower than in the literature to date. The filters can realize highpass, bandpass, lowpass, notch and allpass responses without any changes in the circuit topology. The circuits enjoy the following advantages: minimum number of active elements, no component-matching condition and low active and passive sensitivities.

A portable monitor for fetal heart rate and uterine contraction

The authors describe a low-power lightweight device for long-term ambulatory monitoring of high-risk pregnancies. The portable instrument was developed to monitor fetal heart rate (FHR) and uterine contraction (UC) continuously. It can record the abnormal FHR and UC, and it alerts pregnant women when to go to the hospital to see a physician. The abnormal FHR and UC recorded by the monitor can be analyzed by the associated system, which provides valuable data for the physician as an aid to diagnosis and treatment. The monitor is miniaturized for ambulatory monitoring and is powered by a commercial alkaline 9 V battery.

Novel universal biquad filters using only three followers

Two universal biquad filters that employ only three followers are presented. The proposed networks offer the following advantageous features: realization of highpass, bandpass, lowpass, notch and allpass filtering from the same configuration, minimum passive elements, no requirement for critical matching conditions, and low active and passive sensitivities. Moreover, the current mode circuit is suitable for integrated circuit implementation for using grounded capacitors. PSPICE simulated results are obtained that confirm the theoretical analysis.

Realization of nth-order series impedance function using only (n-1) current-feedback amplifiers

A new configuration for realizing a higher-order series impedance function using current-feedback amplifiers (CFAs) is presented. The nth-order series impedance function employs only (n–1) CFAs and (2n–1) passive elements. The higher order series impedance function can be applied to realize various higher-order highpass and lowpass filters. The passive element values can be easily decided from the coefficients of the filter transfer functions. The use of CFAs simplifies the circuit implementation and makes the proposed circuit attractive for application. Experiments and simulation results are given to confirm the theoretical analysis.

A speech controlled artificial limb based on DSP chip

A speech signal pattern recognition DSP-based system is constructed for real-time control of artificial limb through precise identification of speech and speech command. The portable DSP-based system provides a more effective method to provide multiple control commands than the electromyographic signals from the amputation stump or residual limb. The traditional prosthetic arm can not achieve many complex actions because the EMG of the residual limb is hard to detach from the many different control signals. Goals of multiple command recognition and low cost were achieved by using a portable DSP-based system.

A class of two-current-conveyor-based oscillators employing minimum grounded passive elements

A general configuration is presented for realizing RC sinusoidal oscillators. The configuration employs only two current conveyors and minimum grounded passive elements. Five groups of oscillators associated with different generation current conveyors can be developed from the configuration. A number of oscillator circuits can be obtained from each group by choosing appropriate passive elements. The passive sensitivities of all circuits are quite small. PSpice simulation result has been given to verify the theoretical expectation.

Improved EMG pattern recognition using the distribution plot of cepstrum

In this paper, a real-time on-line plot is developed which recognizes user motion using the first and second cepstral coefficients for pattern recognition of the electromyogram (EMG). The cepstral coefficients, derived from autoregressive coefficients and estimated by a recursive least square algorithm, are used as the recognition features. The features are then discriminated using a modified maximum likelihood distance classifier. The cross distribution of the first and second cepstral coefficients can be plotted real-time and on-line. The physician or user can adjust the specific motions to attain optimal recognition results using this information. Subjects can be trained to contract muscles in specified and easily achievable patterns by the distribution plot. The recognition results can be used as myoelectric prosthetic control, or providing commands for the human-computer interface.

Novel voltage-mode universal filters using two current conveyors

A novel configuration for realizing voltage-mode universal biquad filters with three inputs and two outputs is presented. The configuration uses only two second-generation current conveyors and four passive RC elements. The active and passive sensitivities are quite small. Simulation results that confirm the theoretical analysis are obtained.

A new current-mode universal filter using CCII and OTAs

A new novel current-mode biquad filter using one multiple output second generation current conveyor (CCII), two operational transconductance amplifiers (OTAs), and two grounded capacitors is presented. The filter has three inputs and one output and can realise five different biquad transfer functions simultaneously without any changes in the circuit topology. This circuit enables the circuit characteristics to be electronically tuned. Grounded capacitors are suitable for integrated circuit implementation. An example is given, together with simulated results by PSPICE.