A new multipleinput singleoutput(MISO)type multifunction voltagemode universal biquadratic filter employing single voltage differencing differential input buffered amplifier (VDDIBA), two capacitors, and one resistor are proposed. The proposed structure can realize secondorder low pass, high pass, band pass, band stop, and all pass filter responses without altering the circuit topology. The proposed new filter configuration also provides the following advantageous features, not available simultaneously in any of the single active device /elementbased universal biquad in realizing all the five filter functions known earlier so far: (i) no requirement of any passive component(s) matching condition or inversion of input signal(s), (ii) independent electronic control of angular frequency (
Several multipleinput singleoutput (MISO) or singleinput multipleoutput (SIMO) type currentmode (CM) or voltagemode (VM) universal active filters have been described in the literature because of their flexibility and versatility for practical applications. Among these, MISOtype filters are particularly attractive because the same filter structure can be used for different filter functions. Recently, considerable attention has been devoted for the realization of VM or CM filter structures using different types of single active building block/device [
The purpose of this paper is, therefore, to propose a new MISOtype VM universal biquad employing a single VDDIBA, two capacitors, and a resistor to realize (by appropriate selection of input signal voltage(s)) all the five standard filter functions, namely, low pass (LP), high pass (HP), band pass (BP), band stop (BS), and all pass (AP) without any passive componentmatching requirement(s) or inversion of input signal(s) from the same circuit topology. The presented filter configuration also provides (i) independent electronic control of angular frequency (
The symbolic notation and behavioral model of the VDDIBA (−) are shown in Figures
(a) Symbolic notation, (b) behavioral model of VDDIBA [
The proposed MISOtype voltagemode universal biquadratic filter using single VDDIBA, two capacitors, and a resistor are shown in Figure
The proposed MISOtype voltagemode universal biquad.
A routine circuit analysis (assuming ideal VDDIBA) of Figure
From (
If
If
If
If
If
The expressions for natural frequency (
From (
Considering the nonidealities of the VDDIBA, let
Its active and passive sensitivities can be found as
From (
To confirm workability of the proposed biquad filter, the circuit was simulated using CMOS VDDIBA (as shown in Figure
Proposed CMOS implementation of VDDIBA,
Frequency response.
Phase plot of APF.
Frequency response of APF.
The CMOS VDDIBA is implemented using 0.35
Transistor 


M_{1}–M_{6}  14/1 
M_{7}–M_{9}  14/0.35 
M_{10}–M_{18}  4/1 
M_{19}–M_{22}  7/0.35 
Reference  Number of active elements/devices  Number of capacitors  Number of resistors  Is the realization free from matching condition(s)?  Number of standard filters realized 

[ 
1  2  2  NO  Five 
[ 
1  2  3  NO  Five 
[ 
1  2  2  NO  Five 
[ 
1  4  4  NO  Five 
[ 
1  2  4  NO  Five 
[ 
1  2  3  NO  Five 
[ 
1  2  2  NO  Five 
[ 
1  2  3  NO  Five 
[ 
1  2  1  NO  Five 
Proposed  1  2  1  YES  Five 
.MODEL N NMOS (LEVEL = 3
VTO = 0.5445549
VMAX =
LD =
CGBO =
MJSW = 0.3508721)
.MODEL P PMOS (LEVEL = 3
VTO = −0.7140674
KP =
XJ =
CGBO =
MJSW = 0.5)
A new secondorder voltagemode MISOtype universal biquad filter has been presented. The proposed configuration employs single VDDIBA, two capacitors, and one resistor. The presented biquad (by proper selection of input voltages) can yield secondorder low pass, high pass, band pass, notch and all passfilter responses without altering the circuit topology. The proposed filter configuration also provides the following advantages which are not available simultaneously in any of the single active device/elementbased universal MISOtype VM biquads realizing all the five filter functions: (i) no requirement of any passive component(s) matching condition or inversion of input signal(s), (ii) independent electronic control of angular frequency (