Two new multiple-mode (including voltage, current, transconductance, and transresistance modes) OTA-C universal biquad filters are proposed. The first proposed circuit uses only four operational transconductance amplifiers (OTAs) and two grounded capacitors. The second proposed circuit uses five OTAs and two grounded capacitors. Both the proposed circuits can realize voltage, current, transconductance, and transresistance mode universal filtering responses (low-pass, high-pass, band-pass, notch, and all-pass) from the same topology. The first proposed circuit uses the least number of components. This represents an attractive feature from a chip area and power consumption point of view. The second proposed circuit has no need of extra inverting and non-inverting amplifiers for special input signals. Moreover, both the proposed biquads still have (i) the employment of two grounded capacitors, (ii) cascadable connection of the former voltage-mode stage and the latter current-mode stage, and (iii) low sensitivity performance. H-SPICE simulation results confirm the theoretical analysis.
A fully cascadable (i.e., low/high input impedance for current/voltage input signals and high/low output impedance for current/voltage output signals) mixed-mode (input and output signals can be voltage or current) universal filter biquad by using three differential difference current conveyors (DDCCs), three grounded resistors, and two grounded capacitors is presented in this paper. The proposed biquad can realize the inverting, non-inverting, and differential types universal filtering responses (lowpass, highpass, bandpass, notch, and allpass) from the voltage and current output terminals without changing the filter topology. The proposed circuit is suitable for cascading in all the four possible modes (i.e., voltage, current, transresistance, and transconductance modes). Moreover, the proposed mixed-mode biquad still enjoys (i) using only grounded passive components, (ii) no need of extra inverting and non-inverting amplifiers for special input signals, and (iii) low active and passive sensitivities. This paper also shows how analytical synthesis can be used to produce the proposed mixed-mode filter circuit. H-Spice simulation results confirm the theory.
None of the previously reported mixed-mode universal filters can achieve the following important advantage: no need of component matching conditions. This paper presents a new mixed-mode (including voltage, current, transadmittance, and transimpedance modes) universal biquadratic filter with no need of matching conditions (including no need of component matching and no need of input matching conditions). The proposed filter structure with nine outputs employs two plus-type fully differential current conveyors (P-type FDCCIIs), two grounded capacitors, four grounded resistors and one floating/grounded resistor, which can realize voltage, current, transadmittance, and transimpedance modes universal filtering responses (lowpass, highpass, bandpass, notch, and allpass) from the same topology without matching conditions. Moreover, the proposed circuit still offers many important advantages: the employment of two grounded capacitors, the simultaneous realizations of a lot of filtering functions, using only grounded resistors as the control factors of all filter parameters and gains, having controllable gains in current and transimpedance modes without disturbing filter parameters [Formula: see text], [Formula: see text]/Q, and Q, cascadably connecting the former voltage-mode (VM) stage and the latter current-mode (CM) stage, no capacitors bringing extra poles degrading high-frequency performance, and low active and passive sensitivity performances. H-spice simulations with TSMC 0.18[Formula: see text][Formula: see text]m 1[Formula: see text]P6M CMOS process technology validate theoretical predictions.
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