Second-Order Multifunction Filter with Fully Differential Current Follower

Abstract This paper describes the design of a multifunction biquad filter that can provide multiple transfer functions according to the input and output current ports selected. The filter design is based on a general circuit with five passive elements (three of them are grounded) and one fully differential current follower. This versatile building block is ready to be manufactured by the ON Semiconductor Company and is expected to have impedance and transfer parameters close to the ideal ones in a wide frequency range. The functionality of the filter designed was verified by computer simulation and experimental measurement. The influence of real properties of the active element on the filter characteristics was ascertained

A Novel Pseudo-Differential Integer/Fractional-Order Voltage-Mode All-Pass Filter

The paper presents the first- (integer) and fractional-order case studies of a novel pseudo-differential (P-D) voltage-mode all-pass filter (APF) employing a single differential voltage current conveyor (DVCC), one resistor, and a single grounded capacitor. The proposed filter brings significant reduction of complexity in comparison to available fully-differential or P-D filter topologies. Moreover, it was also shown that fractional-order capacitor can be used for gain response compensation of the proposed APF. The theoretical results of 0.8th and 1st-order APF were verified by Cadence IC6 Spectre simulations using new structure of DVCC via TSMC 0.18 µm CMOS process parameters supplied with ±0.9 V voltages

New Resistorless and Electronically Tunable Realization of Dual-Output VM All-Pass Filter Using VDIBA

In this paper, a new active element called voltage differencing inverting buffered amplifier (VDIBA) is presented. Using single VDIBA and a capacitor, a new resistorless voltage-mode (VM) first-order all-pass filter (APF) is proposed, which provides both inverting and non-inverting outputs at the same configuration simultaneously. The pole frequency of the filter can be electronically controlled by means of bias current of the internal transconductance. No component-matching conditions are required and it has low sensitivity. In addition, the parasitic and loading effects are also investigated. By connecting two newly introduced APFs in open loop a novel second-order APF is proposed. As another application, the proposed VM APF is connected in cascade to a lossy integrator in a closed loop to design a four-phase quadrature oscillator. The theoretical results are verified by SPICE simulations using TSMC 0.18 um level-7 CMOS process parameters with +-0.9 V supply voltages. Moreover, the behavior of the proposed VM APF was also experimentally measured using commercially available integrated circuit OPA860 by Texas Instruments.In this paper, a new active element called voltage differencing inverting buffered amplifier (VDIBA) is presented. Using single VDIBA and a capacitor, a new resistorless voltage-mode (VM) first-order all-pass filter (APF) is proposed, which provides both inverting and non-inverting outputs at the same configuration simultaneously. The pole frequency of the filter can be electronically controlled by means of bias current of the internal transconductance. No component-matching conditions are required and it has low sensitivity. In addition, the parasitic and loading effects are also investigated. By connecting two newly introduced APFs in open loop a novel second-order APF is proposed. As another application, the proposed VM APF is connected in cascade to a lossy integrator in a closed loop to design a four-phase quadrature oscillator. The theoretical results are verified by SPICE simulations using TSMC 0.18 um level-7 CMOS process parameters with +-0.9 V supply voltages. Moreover, the behavior of the proposed VM APF was also experimentally measured using commercially available integrated circuit OPA860 by Texas Instruments

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements