In this letter, an active complex filter with finite transmission zeros is proposed. In order to obtain a complex prototype ladder filter including no inductors, a new circuit transformation is proposed. This circuit is classified into the RiCR filter. It is shown that it includes no negative capacitors when it is obtained through a frequency transformation. The validity of the proposed method is confirmed through computer simulation.

This paper presents a design optimization method for a Gm-C active filter via geometric programming (GP). We first describe a GP-compatible model of a cascaded Gm-C filter that forms a biquadratic output transfer function. The bias, gain, bandwidth, and signal-to-noise ratio (SNR) of the Gm-C filter are described in a GP-compatible way. To further enhance the accuracy of the model, two modeling techniques are introduced. The first, a two-step selection method, chooses whether a saturation or subthreshold model should be used for each transistor in the filter to enhance the modeling accuracy. The second, a bisection method, is applied to include non-posynomial inequalities in the filter modeling. The presented filter model is optimized via a GP solver along with proposed modeling techniques. The numerical experiments over wide ranges of design specifications show good agreement between model and simulation results, with the average error for gain, bandwidth, and SNR being less than 9.9%, 4.4%, and 14.6%, respectively.

This paper proposes an active-RC filter that achieves a wide pseudo-continuous bandwidth-tuning range and a wide gain range with fine steps using a novel switched resistor architecture. A channel-selection filter with the proposed resistor bank is designed for a multi-mode mobile-TV receiver with the 6th order Chebyshev-I topology. The bandwidth, 0.5–6 MHz with 5% steps, supports multiple mobile-TV standards with sufficient margins for process and temperature variations. The filter also accomplishes a 30-dB variable gain range with 6-dB steps, and it relaxes the dynamic range requirement of a succeeding programmable gain amplifier. The power consumption of the filter, 3.4–5.0 mW, is adjustable according to the bandwidth and the signal level. The filter was fabricated with on-chip bandwidth-calibration circuitry in 0.18-µm CMOS and occupied 0.81 mm2.

This paper proposes a technique for two-stage operational amplifiers (OPAMPs) to optimize power consumption according to various channel conditions of wireless communication systems. The proposed OPAMP has the ability of reducing the quiescent current of each stage independently by introducing additional common-mode feedback, therefore more optimization is possible according to the channel conditions than conventional two-stage OPAMPs. The simulations verify the benefits of the technique. As a proof-of-concept topology, the proposed OPAMPs were used in a channel-selection filter for a multi-standard mobile-TV receiver. The power consumption of the filter, 3.4–5.0 mW, was adjustable according to the bandwidth, the noise, and the jammer level. The performance of the filter meets the requirements and verifies the effectiveness of the proposed approach. The filter was fabricated in 0.18-µm CMOS and occupied 0.64 mm2.

A novel electronically tunable high input impedance voltage-mode multifunction filter with single inputs and three outputs employing two single-output-operational transconductance amplifiers, one differential difference current conveyor and two capacitors is proposed. The presented filter can be realized the highpass, bandpass and lowpass functions, simultaneously. The input of the filter exhibits high input impedance so that the synthesized filter can be cascaded without additional buffers. The circuit needs no any external resistors and employs two grounded capacitors, which is suitable for integrated circuit implementation.

In this letter a new structure of multifunctional frequency filter using a universal voltage conveyor (UVC) is presented. The multifunctional circuit can realize a low-pass, high-pass and band-pass filter. All types of frequency filter can be realized as inverting or non-inverting. Advantages of the proposed structure are the independent control of the quality factor at the cut-off frequency and the low output impedance of output terminals. The computer simulations and measuring of particular frequency filters are depicted.

Despite the extensive literature on current conveyor-based universal (namely, low-pass, band-pass, high-pass, notch, and all-pass) biquads with three inputs and one output, no filter circuits have been reported to date which simultaneously achieve the following seven important features: (i) employment of only two current conveyors, (ii) employment of only grounded capacitors, (iii) employment of only grounded resistors, (iv) high-input and low-output impedance, (v) no need to employ inverting type input signals, (vi) no need to impose component choice conditions to realize specific filtering functions, and (vii) low active and passive sensitivity performances. This letter describes a new voltage-mode biquad circuit that satisfies all the above features simultaneously, and without trade-offs.

Despite the extensive literature on current conveyor-based voltage-mode universal biquads with single input and multiple outputs, no filter circuits have been reported to date which simultaneously achieve all of the advantageous features: (i) employment of only one differential difference current conveyor (DDCC), (ii) employment of only two grounded capacitors, (iii) employment of only three resistors, (iv) simultaneous realization of voltage-mode low-pass, band-pass, and high-pass filter signals from the three output terminals, respectively, (v) no need to employ inverting type input signals, and (vi) no need to impose component choice.

This paper presents a partially resonant active filter based on a digital PWM control circuit with a DSP that can improve the power factor and input current harmonic distortion factor of distributed power supply systems in communications buildings. The steady-state and dynamic characteristics of this active filter are analyzed experimentally and the relationship between the control variables of digital control circuit with the DSP and performance characteristics such as regulation of the output voltage, input power factor, input current harmonic distortion factor, boundaries of stabilities and transient response are defined. Using the partially resonant circuit, the efficiency is over 91%, which is 0.9 point higher than that of non-resonant circuit and the high frequency switching noise is suppressed. Furthermore, the digital control strategy with the DSP proposed in this paper can realize the superior transient response of input current and output voltage for the step change of load, the power factor over 0.99 and total harmonic distortion factor less than 1.1%.

Despite the extensive literature on current conveyor-based voltage-mode first-order all-pass filters, no filter circuits have been reported to date that simultaneously achieve all of the advantageous features: (i) the employment of only one current conveyor, (ii) the employment of only one grounded capacitor, (iii) the employment of only one resistor, (iv) no need to impose component choice conditions, and (v) low active and passive sensitivities. In this letter, we describe such a filter structure with all of the above features simultaneously present, without trade-offs. H-Spice simulation results using the TSMC025 process and 1.25 V supply voltages validate the theoretical predictions.

A novel first order voltage-mode non-inverting and inverting output of all-pass filter using an inverting type current conveyor (ICCII) is given. It is a first announced about a first-order voltage-mode non-inverting and inverting output of all-pass filter at the same configuration in the literature. The proposed circuit is verified using HSPICE simulation with attractive results.

In this paper, is shown an approach to realize leapfrog structures obtained from proto-type passive RLC ladder filters using current differencing buffered amplifiers (CDBA) as active elements. The use of the CDBA's provides advantages that the realization procedure is simplified and the number of active components required is reduced. The approach is quite suitable for the realization of band-pass ladder filters, which generally requires a complicated structure to simulate LC series and/or parallel resonant branches by the conventional opamp-based leapfrog filters. A simple circuit configuration of the CDBA suitable for high frequency and low power supply voltage applications is also presented. As design examples, a fifth-order Butterworth lowpass ladder filter and a sixth-order Chebyshev bandpass ladder filter are designed. The effectiveness and the correctness of the proposed approach and the characteristics of the proposed filters are verified and examined through computer simulation.

This article addresses the problem of designing and implementing multigigabit post-detection filters for application in optical communication systems using optical soliton pulses. The designed filters have the main advantages of full integration, electrically adjustable frequency response and active input and output impedance match.

In this letter, a realization of current-mode active filter using current followers as active element is described. We show the constructions of second-order lowpass, highpass and bandpass filters. The high-order filters can be realized by a cascade connection of these second filters. As examples, the second-order lowpass and highpass filters are designed for frequency of 5 MHz. The effectiveness of the proposed method is demonstrated through SPICE simulation.

In this paper, two universal building blocks for complex filter using CCIIs, CFCCIIs, grounded resistors and grounded capacitors are presented. These can be used to realize various complex bandpass filters with arbitrary order. The paper shows that the response error of the proposed circuit caused by nonideality of active components is more easily compensated than that of the conventional one employing op-amps, and that the sensitivities for all components are relatively small. Experimental results are used for verifying the validity of the proposed circuits.

In this paper, implementation of a first-order active complex filter with variable parameter using operational transconductance amplifiers (OTAs) and grounded copacitors is presented. The proposed configurations can be used as s key building block to realize high-order active complex filters with variable parameter in cascade and leapfrog configuration. Experimental results which are in good agreement with theoretical responses are also given o demonstrate the feasibility of the proposed configurations.

This letter presents a realization of active current-mode resonator with complex coefficients using CCIIs. The resonator can be used for cascade or leapfrog configuration of high-order bandpass filters with complex coefficients. For realizing the resonators, only the grounded capacitors and the grounded resistors as passive elements are required, therfore the resonator is suitable for the integrated circuit realization. The letter shows that the response error of the proposed circuit caused by nonideality of active components is more easily compensated than that of voltage-mode counterpart. Experimental result is used for verifying the feasibility of the proposed resonator.

A design of current-mode continuous-time filters for low voltage and high frequency applications using complementary bipolar current mirror pairs is presented. The proposed current-mode filters consist of simple bipolar current mirrors and capacitors and are quite suitable for monolithic integration. Since the filters are based on the integrator type of realization, the proposed method can be used for a wide range of applications. The frequency of the filters can easily be changed by the DC controlling current. A fifth-order Butterworth and a thirdorder leapfrog filter with tunable cutoff frequencies from 20 MHz to 100 MHz are designed as examples and simulated by SPICE using standard bipolar parameters.

According as the fine LSI process technique develops, the technique to reduce power dissipation of high-frequency integrated analog circuits is getting more important. This paper describes a design of high-frequency integrator with low power dissipation for monolithic leapfrog filters. In the design of the conventional monolithic integrators, there has been a great dfficulty that a high-frequency integrator which can operate at low supply voltage cannot be realized without additional circuits, such as unbalanced-to-balanced conversion circuits and common-mode feedback circuits. The proposed integrator is based on the Miller integrator. By a PNP current mirror circuit, high CMRR is realized. However, the high-frequency characteristic of the integrator is independent of PNP transistors. In addition, it can operate at low supply voltage. The excess phase shift of the integrator is compensated by insertion of the compensation capacitance. The effectiveness of the proposed technique is confirmed by PSPICE simulation. The simulation results of the integrator shows that the common-mode gain is efficiently low and the virtual ground is realized, and that moderate phase compensation can be achieved. The simulation results of the 3rd-order leapfrog filter using the integrator shows that the 50 MHz-cutoff frequency filter is obtained. Its power dissipation in operating 2 V-supply voltage is 5.22 mW.

Design techniques are presented for high performance microstrip bandpass filters using GaAs FETs for loss compensation. The filters are based on conventional planar filter topologies with the addition of GaAs FET negative resistance circuits to amplify the signal within the resonators via a reflection-mode of amplification. Three practical filters have been demonstrated using these negative resistance techniques: (1) A filter employing an active loop configuration, (2) a dual-mode microstrip ring resonator filter, and (3) an end-coupled half-wavelength resonator filter. The investigation of this negative resistance method of loss compensation has led to the development of an exciting new type of miniaturised filter which employs MIC microstrip resonators with MMIC negative resistance chips bonded into the filter for loss compensation. This approach has the advantage of combining the proven capabilities of established MIC microstrip filter topologies with the excellent reproducibility of the MMIC loss compensation circuits.