Multiple-input single-output current-mode multifunction filter using current differencing transconductance amplifiers

Current Processing Current Tunable Universal Biquad Filter Employing Two CCTAs and Two Grounded Capacitors

“…The proposed filter offers the following advantages: 1) employment of only two active elements; 2) ability of realizing all current-mode standard filtering functions; 3) employment of minimum number of grounded capacitors (only two) to realize any biquad filtering function; 4) low sensitivity figures; 5) electronically orthogonal tunability of ω 0 and Q; 6) availability of explicit current output (i.e. high impedance output node) without requiring any additional active elements; 7) no requirement of components matching conditions to get all filtering responses; 8) no requirements of inverting-type input current signal(s) and double input current signal(s) to realize the filtering response(s) in the design, all of which are not available simultaneously in any of the previously reported current-controlled current-mode biquad filter of [15][16][17][18][19][20][21][22][23][24][25][26][27]. With above mentioned features, it is very suitable to realize the proposed circuit in monolithic chip to use in battery powered, portable electronic equipments such as wireless communication system devices.…”

“…Few more three input single output currentmode filters based on two active elements in the form of CDTA [22], CFTA [23], VDTA [24] and CCTA [25] are also proposed in the literature. Each circuit [22][23][24][25] consists of two grounded capacitors and realizes all the standard filtering functions but they also require minus input current signal(s) [22][23][24] or/and double input current signal(s) [22][23][24][25] to realize at least one filter function. Other novel circuits based on two CCCCTAs [26,27] each having two grounded capacitors can also be used as three input single output tunable current-mode filter but they still require minus input current signal [26] or matching conditions [27] to realize AP response.…”

“…So there is a growing interest towards designing of electronically tunable filters to compensate for deviation in the circuit due to process tolerance, parasitic, temperature drift and component aging. During the last one decade and recent past, several electronically tunable MISO type current-mode active filters have been proposed in the literature [15][16][17][18][19][20][21][22][23][24][25][26][27], using different currentmode active elements such as second generation current controlled current conveyor (CCCII) [15][16][17][18][19][20][21], current differencing transconductance amplifier (CDTA) [22], current follower transconductance amplifier (CFTA) [23], voltage differencing transconductance amplifier (VDTA) [24], current controlled transconductance amplifier (CC-TA) [25] and current controlled current conveyor transconductance amplifier (CCCCTA) [26,27] etc.…”

“…SIMO filters [3][4][5][6][7][8][9][10][11][12][13] simultaneously realize different filtering functions (in general three or more) at different outputs, without changing the connection of the input signal. On the other hand MISO filters [15][16][17][18][19][20][21][22][23][24][25][26][27] can realize multifunction filtering responses at single output terminal by altering the way in which multi-input signals are connected. Moreover, the MISO configuration in comparison with SIMO configuration may lead to a reduction in number of active elements for circuit realization and hence, seems to be more suitable than that of SIMO configuration to realize all the standard biquad filter functions.…”

Current Mode Universal Filter Using Single Current Controlled Differential Difference Current Conveyor Transconductance Amplifier

“…The study of MISO universal filters [13]- [24] based on current mode ABB reveals that these circuits suffer one or more of the following weakness:…”