Narrow Results

The power quality has become a major concern since late 1980's. There has been increasing interest in studying power quality problems, one of which is the existence of the current/voltage harmonics. In order to eliminate these harmonics, different methods have so far been proposed and developed. In this paper, line current harmonics reduction is achieved by using an active filter. More specifically, our aim is to introduce a proper control design method for the current control part of the active filter. To achieve the goal, two different predictive controllers are examined. Due to the existing physical constraints (switching frequency and computational limits) in real applications, a new predictive control approach is proposed. The performance of this controller is compared to those obtained by two existing predictive controllers as well as commonly used PI controller through computer simulations considering various circumstances.

In this paper, a CMOS current controlled current differencing buffered amplifier (C-CDBA) realization is presented. Also, a new first-order all-pass filter that compensates for some C-CDBA non-idealities is given as an application example. The all-pass filter circuit has low output impedance for easy cascadability and it can be made electronically tunable using the proposed C-CDBA implementation. The theoretical results are verified with SPICE simulations.

A new single input and five outputs high input impedance voltage-mode universal biquadratic filter using three DVCCs, five passive components is presented. The proposed circuit offers the following features: high input impedance, realization of all the standard filter functions, that is, high-pass, band-pass, low-pass, band reject and all-pass filters simultaneously, the use of grounded capacitor, orthogonal control of ω₀ and Q, no need to employ inverting type input signals, and no need to impose component choice except realizing the all-pass filter signal. A new quadrature oscillator circuit is also realized. PSPICE simulations using 0.35 μm TSMC CMOS parameters confirm the validity of the proposed circuit.

In this paper, twelve new circuit configurations for realization of first-order, second-order voltage-mode all-pass and notch filters with high input impedance and low output impedance are presented. The proposed circuit configurations use two plus type DDCCs, and two impedances. The circuits use one grounded capacitor and two grounded resistors for realizing first-order all-pass filters, and two grounded capacitors and two resistors for realizing second-order all-pass/notch filters. High input impedance and low output impedance of the configuration enable the circuits to be cascaded without additional buffers. As an application, a quadrature oscillator is realized. The theoretical results are verified with PSPICE simulations using 0.5 μm CMOS parameters.

This paper presents two new first-order voltage-mode (VM) cascadable all-pass (AP) sections, employing two differential voltage current conveyors (DVCCs) and three grounded passive components. Both circuits possess high input and low output impedance, which makes them easily cascadable. Non-ideality aspects and parasitic effects are also studied. As an application, a quadrature oscillator is designed using the proposed circuit. The proposed circuits are verified through PSPICE simulations using 0.5 μm CMOS parameters.

One approach to design self-tuning g_m-C biquad band-pass filter is considered in this paper. The phase control loop is introduced to force filter central frequency to be equal to input signal frequency what is achieved by adjusting the amplifier transconductance g_m. Thanks to that, the filter is robust to parameter perturbations and it can be used as a selective amplifier. In the full tuning range, it has a constant maximum gain at central frequency as well as a constant bandwidth. The 0.25 μm SiGe BiCMOS technology was used during design and verification of the band-pass filter. The filter has 26 dB gain, quality factor Q = 20 and central frequency up to 150 MHz. Simulation results indicate that the total in-band noise is 59 μV_rms, the output third intercept point OIP3 = 4.36 dB and the dynamic range is 35 dB. Maximal power consumption at 3 V power supply is 1.115 mW.

This paper presents an active-RC continuous time filter in 0.18 μm standard CMOS technology intended to operate on a very low supply voltage of 0.5 V. The filter designed, has a 5th order Chebyshev low pass response with a bandwidth of 477 kHz and 1-dB passband ripple. A low-power operational transconductance amplifier (OTA) is designed which makes the filter realizable. The OTA uses bulk-driven input transistors and feed-forward compensation in order to increase the Dynamic Range and Unity Gain Bandwidth, respectively. The paper also presents an equivalent circuit of the OTA and explains how the filter can be modeled using descriptor state-space equations which will be used for design centering the filter in the presence of parasitics. The designed filter offers a dynamic range of 51.3 dB while consuming a power of 237 μW.

In this paper, we present, at transistor level, a very low complexity Gaussian monocycle pulse generator/modulator for DPSK low voltage and low power tunable ultra-wideband (UWB) applications. The pulse generator, simulated in a SMIC 0.13 μm CMOS technology, provides a tunable, both in pulse width duration and repetition time, Gaussian monocycle compliant with the sub-GHz ETSI band and suitable to be used in UWB radio applications. The preliminary IC simulation results show a pulse duration from 1 ns up to 20 ns with good pulse symmetry and with the DPSK modulation capability. The circuit power consumption is about 1 mW from a 1.8 V power supply.

In this paper, we present a low-voltage tunable active filter for microwave applications. The proposed filter is based on a single-transistor active inductor (AI), that allows the reduction of circuit area and power consumption. The three active-cell bandpass filter has a 1950 MHz center frequency with a -1 dB flat bandwidth of 10 MHz (Q ≈ 200), a shape factor (30–3 dB) of 2.5, and can be tuned in the range 1800–2050 MHz, with constant insertion loss. A dynamic range of about 75 dB is obtained, with a P1dB compression point of -5 dBm. The prototype board, fabricated on a TLX-8 substrate, has a 4 mW power consumption with a 1.2 V power supply voltage.

This paper describes the design of a self-tuning OTA-C notch filter (NF), based on a phase control loop concept. The phases of filter input and output signals are compared and the phase error is used to generate the control voltage, which adjusts the transconductances of operational transconductance amplifiers (OTAs) and, consequently, tunes the NF center frequency without quality factor variation. The proposed solution is robust to filter parameter variations. The filter is implemented in 0.13$\mu$m SiGe BiCMOS technology. Under the typical circuit operating conditions, the center frequency tuning is within the range from 70MHz up to 150MHz, with tuning error less than 1%. The power consumption is less than 3.6mW, the 1dB gain compression point is $-$2.5dBm, the input (IIP3) and output (OIP3) intercept points are 3.47 and 9.07dBm, respectively, and the total filter effective noise voltage is 4.35$\mu$Vrms. The filter structure is suitable for complementary metal-oxide-semiconductor (CMOS) implementation.

In this paper, we present a new method increasing quality factor of active filter structure in the literature and a new designed filter. The new method is easily applied to all different filter modes with the proper feedback circuit. The center frequency of the filter remains constant as quality factor of filter increases. Also, quality factor can be also tuned electronically by changing the biasing current of the feedback circuit. Furthermore, the performance of the method is demonstrated by CMOS simulation of differential voltage current conveyor and transconductance amplifier. Quality factor value of the filter can also be easily adjusted electronically between 1 and 20 with the presented method. Finally, an application example of the presented method is presented for double tuned amplifier for intermediate frequency pre-amplifier of FM receiver.

According to the situation of serious harmonic pollution and lower power factor in enterprise’s distribution system with photo-voltaic, an analysis and a summary on possible problems of power quality were made. A governance program that is to install active filter on enterprise’s distribution system with photo-voltaic has been proposed, and the feasibility of this program has been validated with an instance. Firstly, the authentic date from an enterprise’s flied test was analyzed and the present problems of enterprise’s distribution system were simulated with matlab. Then, after the active filter is installed and the simulation of the improved systems turned out that the content of each harmonic decreased apparently. At the same time, the power factor improved to the standard on power quality.