Voltage-controlled filter

About: Voltage-controlled filter is a research topic. Over the lifetime, 5514 publications have been published within this topic receiving 70872 citations. The topic is also known as: VCF.

Hairpin microstrip bandpass filter for millimeter-wave applications

Abstract: A compact microstrip bandpass filter is proposed in this paper for millimeter-wave applications. The filter consists of three new non-uniform coupled-line modified hairpin resonators. The filter is designed to exhibit a fractional bandwidth of about 5.0 % at a center of frequency of approximately 34 GHz. The shapes of the hairpin resonators are modified to suppress the unwanted spurious harmonic response. As a result, the filter exhibits very wide stopband with a rejection level better than 10-dB. In addition, the filter shows a transmission zero close to upper edge of the desired passband which enhances the selectivity of the passband. The filter design is successfully realized on a RT/Duroid 6002 with a dielectric constant of 2.94 and a thickness of 127μm. The filter is simulated, and fabricated to demonstrate the proposed technique where excellent agreement is obtained.

A New DVCC+ Based Second-Order Current-Mode Universal Filter Consisting of Only Grounded Capacitors

Abstract: In this paper, a new second-order current-mode universal filter using only two plus-type differential voltage current conveyors, three resistors and two grounded capacitors is proposed. The proposed circuit with two identical inputs and three outputs can simultaneously provide second-order high output impedance low-pass, band-pass and notch filter responses. Also, it can realize high-pass and all-pass filter responses with interconnection of relevant output currents. It can be easily tuned electronically. It can be operated properly at high frequencies. A number of simulations based on SPICE program and an experimental test are achieved in order to demonstrate the performance of the proposed filter.

Silicon-Integrated Differential Bandpass Filters Based on Recursive and Channelized Principles and Methodology to Compute Their Exact Noise Figure

Abstract: In this paper, two silicon-integrated differential active bandpass filters are presented. The first one is a recursive filter based on a cellular approach. This circuit is independently tunable in terms of power transmission gain, center frequency, and bandwidth. The chip surface is less than 1.4 mm2. For this prototype, measurements demonstrate a 1.9-2.4-GHz center-frequency tuning range with a typical gain of 15 dB and a 3-dB bandwidth of 60 MHz. Gains of up to 40 dB and bandwidths as low as 20 MHz are also achievable in the 2.05-2.38-GHz range. Subsequently, the design of an integrated three-branch channelized bandpass filter is addressed. The proposed filter uses an active power splitter at its input. Moreover, the channels are based on elementary first-order tunable recursive stages derived from the previously described topology, thus making the overall filter fully reconfigurable. This second circuit, whose layout size is smaller than 3 mm2, can exhibit 3-dB bandwidths of ap90 MHz and gains of up to 20 dB within a 1.95-2.23-GHz tuning range. Controllable high selectivity for each rejected band can be obtained through the generation of adjustable out-of-band transmission zeros. Furthermore, a dual-band behavior is also feasible through this filter. To conclude, an original method to extract the exact noise figure of differential circuits is reported, and applied to the filter prototypes developed in this study. The Philips QUBIC4 0.25-mum silicon BiCMOS process has been used for the design of the two circuits presented

Phase-Locked Loop Based Controller for Adjusting an Adaptive Continuous-Time Filter

Abstract: A direct conversion radio-frequency (RF) receiver includes a controller and an adaptive continuous-time filter. The adaptive continuous-time filter receives a multiple-bit control signal generated by the controller to adjust a characteristic of the continuous-time filter. The controller generates the multiple-bit control signal in response to process variation in the semiconductor material used to implement the controller and the adaptive continuous-time filter. A method for tuning an adaptive continuous-time filter comprises determining a RC time constant, converting the RC time constant to a digital word, comparing a select bit of the digital word to a respective bit of a predetermined reference word to generate a control bit, applying the control bit to an adjustable element to modify the RC time constant, repeating the determining, converting, comparing and applying steps until the control bits generate an output word and providing the output word to the adaptive continuous-time filter.

Voltage-mode multifunction biquadratic filter based on simple CMOS OTAs

Abstract: A voltage-mode versatile multifunction filter with four inputs and three outputs biquadratic filter based on simple CMOS operational transconductance amplifiers (OTAs) is presented. By appropriately connecting the input and output terminals, the proposed circuit can work as either a single-input multiple-output (SIMO) or a multiple-input single-output (MISO) filter without changing the circuit topology. When the circuit functions as a SIMO filter, it provides bandpass (BP), lowpass (LP) and bandstop (BS) voltage responses with grounded capacitors. When it functions as a MISO filter, the circuit can realize all the standard non-inverting and inverting second-order filter functions. The parameters ω 0 and Q can be set orthogonally by adjusting the circuit components. For realizing all the filter responses, no critical matching condition is required, no inverting-type input signal is imposed and all the incremental parameter sensitivities are low. The simulation results confirm the theoretical analysis.