A Compact Electronically Controllable Biquad Filter Synthesizing from Parallel Passive RLC Configuration

Universal Filter Based on Compact CMOS Structure of VDDDA

“…Table 1 compares the proposed universal biquad filter with previous biquad filters using the VDDDA [13][14][15][16][17][18][19][20][21][22][23][24]. These biquad filters are the multiple input multiple output (MIMO) [13,14,23], multiple input single output (MISO) [16,18,19,21,24] and single input multiple output (SIMO) [14,17,20,22] configurations. The design technique used in [13][14][15]17,[19][20][21][22] were based on two integrator loops, while the filters in [16,18,23,24] were based on a passive RLC circuit.…”

“…Additionally, some VDDDA-based voltage-mode filters can cascade without the requirement of additional buffer devices. In this point of view, several active biquad filters using the VDDDA have been reported [13][14][15][16][17][18][19][20][21][22][23][24]. The voltage mode biquad filters using the voltage differential difference device (called the differential difference current conveyor transconductance amplifier (DDCCTA)) have been also proposed in references [25][26][27].…”

“…The voltage mode biquad filters using the voltage differential difference device (called the differential difference current conveyor transconductance amplifier (DDCCTA)) have been also proposed in references [25][26][27]. These biquad filters can be classified into two categories based on their design techniques, which are based on two integrator loops [13][14][15]17,[19][20][21][22]25,27] and based on a passive resistorinductor-capacitor (RLC) circuit [16,18,23,24,26]. The RLC based biquad filters proposed in [16,18,23,24] have very simple circuitry with a single VDDDA.…”

“…These biquad filters can be classified into two categories based on their design techniques, which are based on two integrator loops [13][14][15]17,[19][20][21][22]25,27] and based on a passive resistorinductor-capacitor (RLC) circuit [16,18,23,24,26]. The RLC based biquad filters proposed in [16,18,23,24] have very simple circuitry with a single VDDDA. However, these biquad filter realized from the RLC circuit have the following disadvantages: they consist of a floating capacitor [16,18,24,26], the natural frequency (f 0 ) and quality factor (Q) are not orthogonally controlled by changing the transconductance of the VDDDA [16,18,23,24], high impedance nodes at the input stage and a low impedance node at the output stage are not obtained [16,18,23,24,26] and additional circuits such as the unity gain inverting voltage amplifier or double-gain voltage amplifier are required for obtaining many filtering functions [16,18,24,26].…”

“…The RLC based biquad filters proposed in [16,18,23,24] have very simple circuitry with a single VDDDA. However, these biquad filter realized from the RLC circuit have the following disadvantages: they consist of a floating capacitor [16,18,24,26], the natural frequency (f 0 ) and quality factor (Q) are not orthogonally controlled by changing the transconductance of the VDDDA [16,18,23,24], high impedance nodes at the input stage and a low impedance node at the output stage are not obtained [16,18,23,24,26] and additional circuits such as the unity gain inverting voltage amplifier or double-gain voltage amplifier are required for obtaining many filtering functions [16,18,24,26]. Two-integrator loop-based biquad filters with high input impedance were obtained in references [13][14][15]17,[19][20][21][22]27].…”