Current-Processing Current-Controlled Universal Biquad Filter

This paper presents a current-processing current-controlled universal biquad filter. The proposed filter employs only two current controlled current conveyor transconductance amplifiers (CCCCTAs) and two grounded capacitors. The proposed configuration can be used either as a single input three outputs (SITO) or as three inputs single output (TISO) filter. The circuit realizes all five different standard filter functions i.e. low-pass (LP), band-pass (BP), high-pass (HP), band-reject (BR) and all-pass (AP). The circuit enjoys electronic control of quality factor through the single bias current without disturbing pole frequency. Effects of non-idealities are also discussed. The circuit exhibits low active and passive sensitivity figures. The validity of proposed filter is verified through computer simulations using PSPICE

FULLY INTEGRATED MULTIFUNCTION TRANS-IMPEDANCE MODE BIQUAD FILTER

This paper presents a new trans-impedance-mode biquad filter which simultaneously, realizes the multifunction filtering outputs such as low pass (LP), band pass (BP), high pass (HP) and band reject (BR). The presented filter topology consists of only single active element as voltage differencing transconductance amplifier (VDTA) along with two grounded capacitors and two MOS implemented grounded resistors. So, the proposed TIM filter structure is fully integrable and canonical in nature. Apart from these, the proposed filter also enjoys the desirable features such as low active and passive sensitivities, low power consumption and orthogonal tunability of pole frequency and quality factor by electronic means. The presented filter is simulated using PSPICE in 0.18 µm CMOS process

Tunable Mixed-Mode Voltage Differencing Buffered Amplifier-Based Universal Filter with Independently High-Q Factor Controllability

This paper proposes the design of a mixed-mode universal biquad configuration, which realizes generic filter functions in all four possible modes, namely voltage mode (VM), current mode (CM), transadmittance mode (TAM), and transimpedance mode (TIM). The filter architecture employs two voltage differencing buffered amplifiers (VDBAs), two resistors and two capacitors, and can provide lowpass (LP), bandpass (BP), highpass (HP), bandstop (BS), and allpass (AP) biquadratic filtering responses without any circuit alteration. All passive elements used are grounded, except VM. The circuit not only allows for the electronic tuning of the natural angular frequency (o), but also achieves orthogonal tunability of the quality factor (Q). It also provides the feature of availability of output voltage at the low-output impedance terminal in VM and TIM, and does not require inverting-type or double-type input signals to realize all the responses. Moreover, in all modes of operation, the high-Q filter can be easily obtained by adjusting a single resistance value. Influences of the VDBA nonidealities and parasitic elements are also discussed in detail. PSPICE simulations with TSMC 0.18-µm CMOS process parameters and experimental testing results with commercially available IC LT1228s have been used to validate the theoretical predictions