Systematic Design of Pseudo-Differential Frequency Filter

In the paper, the theory of systematic design frequency filters is described. The result is a fourth-order pseudo-differential frequency filter operating in the voltagemode and implemented as a cascade connection of two basic second-order blocks. The filter is able to realize the low-pass filtering functions. The basic block employs three active elements and four passive elements. The filter is characterized by a minimum number of passive elements and high output impedance. Filter analysis examines the magnitude, phase, common-mode rejection ratio signal, and behavior of filters while reducing the recommended voltage. The proper functionality of the filter is verified by simulations and experimental measurements for two different interconnections

Electronically Tunable First Order AP/LP and LP/HP Filter Topologies Using Electronically Controllable Second Generation Voltage Conveyor (CVCII)

In this paper two new first order filter topologies realizing low-pass/all-pass (LP/AP) and low-pass/high-pass (LP/HP) outputs using electronically controllable second generation voltage conveyors (CVCIIs) are presented. Unlike second generation voltage conveyors (VCII), in CVCII each performance parameter, including ports, parasitic impedances, current and/or voltage gains can be electronically varied. Here, in particular, the proposed filter topologies are based on two CVCIIs, one resistor and one capacitor. In the first topology VLP/IAP/VAP and in the second topology ILP/VLP/IHP/VHP outputs are achievable, respectively. However, the current and voltage outputs are not achievable simultaneously and a floating capacitor is used. A control current (Icon) is used to change the first CVCII Y port impedance, which sets the filter −3 dB frequency (f0) of all the outputs. Moreover, in the second topology, the gains of HP and AP outputs are electronically adjusted by means of a control voltage (Vcon). Favorably, no restricting matching condition is necessary. PSpice simulations using 0.18 µm CMOS technology and supply voltages of ±0.9V show that by changing Icon from 0.5 µA to 50 µA, f0 is varied from 89 kHz to 1 MHz. Similarly, for a Vcon variation from −0.9 V to 0.185 V, the gains of IAP and IHP vary from 30 dB to 0 dB and those of VAP and VHP vary from 100 dB to 20 dB. The total harmonic distortion (THD) is about 8%. The power consumption is from 0.385 mW to 1.057 mW

Pole frequency and pass-band gain tunable novel fully-differential current-mode all-pass filter

Minaei, Shahram (Dogus Author) -- Göknar, İzzet Cem (Dogus Author) -- Conference full title: IEEE International Symposium on Circuits and Systems, ISCAS 2015; Lisbon; Portugal; 24 May 2015 through 27 May 2015In this paper, a new realization of a fully-differential (F-D) first-order all-pass filter (APF) operating in current mode (CM) is presented. In the proposed F-D CM APF a single adjustable current amplifier (ACA) and two current followers (CFS) with non-unity gain are used as active building blocks. Considering the input intrinsic resistance of CFS as useful active filter parameter, the proposed filter employs only a floating capacitor as external passive component. The pole frequency of the proposed resistorless circuit can be tuned via mutual change of input intrinsic resistance of CFS while the filter pass-band gain by means of gain of ACA. The theoretical results are verified by SPICE simulations, where TSMC 0.18 μm level-7 SCN018 CMOS process parameters were used