Universal current-mode biquad filter using dual output current differencing transconductance amplifier

High-performance current differencing transconductance amplifier and its application in precision current-mode rectification

“…A 2 nd -order current-mode filter employing a single CDTA is described in the paper as a revisited version of circuits described in [1], [12], and [13]. The remaining filter components are two grounded capacitors and one virtually-grounded resistor.…”

“…The above combinations of input excitations (8), (10), (14) and the summing of output currents (7), (12), (13) in order to obtain several types of transfer functions are frequently used in the literature [8], [15], [16]. However, the corresponding error analysis of the consequences of matching errors has not been published.…”

“…In this paper, a current-mode filter, starting from the topologies in [1] and [13], and consisting of a single ZC-CDTA, two grounded capacitors and one resistor, which is virtually grounded through the low-impedance CDTA input, is described. No Q-limitation from [12] exists for this filter.…”

“…However, they can only serve as low-pass and band-pass filters, and the output currents flow via the working resistances. In [13], the circuit from [1] is complemented with one resistor, namely R 3 , and such a structure is described as a universal current-mode biquad, providing four basic transfer functions (low-pass, band-pass, high-pass, and band-reject) simultaneously. However, this circuit labors with the following drawbacks: 1) Only the output current of the low-pass section flows to an independent load.…”

Electronically tunable current mode biquad filter based on single VDTA and grounded passive elements

“…However, with a view to being adaptable towards low cost, low power, simplicity and area saving of the circuits, it is beneficial to realize CM biquad filter using single active element. Thus, in recent years a number of CM biquad filter using single active elements are reported in the literature [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] employing CCII [18,23], FDCCII [11,24], DVCC [12], CCCII [20] , CFTA [9,15,21], VDTA [10,13,22], CDTA [14,17] CCTA [16], CCCCTA [19], etc., whose features are compared and summarized in Table 1. After comparative study of the circuits endorsed in Table I, it has been concluded that these reported circuits unfortunately, suffer from at least one of the following disadvantages.…”