Electronically Tunable Resistorless Mixed Mode Biquad Filters

This paper presents a new realization of elec¬tronically tunable mixed mode (including transadmittance- and voltage-modes) biquad filter with single input, three outputs or three inputs, single output using voltage differ-encing transconductance amplifier (VDTA), a recently introduced active element. It can simultaneously realize standard filtering signals: low-pass, band-pass and high-pass or by selecting input terminals, it can realize all five different filtering signals: low-pass, band-pass, high-pass, band-stop and all-pass. The proposed filter circuit offers the following attractive feature: no requirement of invert-ing type input signal which is require no addition circuit, critical component matching conditions are not required in the design, the circuit parameters ω0 and Q can be set orthogonally or independently through adjusting the bias currents of the VDTAs, the proposed circuit employs two active and minimum numbers of passive components. Fur-thermore, this filter was investigated from the point of view of limited frequency range, stability conditions, effects of parasitic elements and effects of non-ideal and sensitivity. Thus, taking these effects and conditions into considera¬tion, working conditions and boundaries of this filter are determined. We also performed Monte Carlo, THD and noise analyses. Simulation results are given to confirm theoretical analyses

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

Voltage Differencing Current Conveyor Based Voltage-Mode and Current-Mode Universal Biquad Filters with Electronic Tuning Facility

The objective of this study is to present four new universal biquad filters, two voltage-mode multi-input-single-output (MISO), and two current-mode single-input-multi-output (SIMO). The filters employ one voltage differencing current conveyor (VDCC) as an active element and two capacitors along with two resistors as passive elements. All the five filter responses, i.e., high-pass, low-pass, band-pass, band-stop, and all-pass responses, are obtained from the same circuit topology. Moreover, the pole frequency and quality factor are independently tunable. Additionally, they do not require any double/inverted input signals for response realization. Furthermore, they enjoy low active and passive sensitivities. Various regular analyses support the design ideas. The functionality of the presented filters are tested by PSPICE simulations using TSMC 0.18 µm technology parameters with ± 0.9 V supply voltage. The circuits are also justified experimentally by creating the VDCC block using commercially available OPA860 ICs. The experimental and simulation results agree well with the theoretically predicted results

Electronically Tunable SIMO type Mixed-mode Biquadratic Filter using Single FTFNTA

629-637In this manuscript, a new electronically tunable single input multiple output (SIMO) type a mixed-mode biquad filter is proposed. It is made up of a single Four Terminal Floating Nullor Transconductance Amplifier (FTFNTA) as an Active Building Block, one resistor, and two grounded capacitors. So, the presence of grounded capacitors renders the circuit compatible for IC development. As it is a SIMO type structure so no matched inputs are required. Also, the matching of passive components is not an issue with this design. For current as an input, the proposed design can generate current mode (low-pass, high-pass, and band-pass) filters as well as transimpedance mode (band-pass and inverting low-pass) filters. Similarly, when given a voltage as input, it can generate voltage mode (high-pass and inverting band-pass) filters as well as transadmitance mode (inverting band-pass and inverting high-pass) filters at the same time. The pole frequency (ω0) and quality factor (Q0) of designed filters can be tuned electronically through a grounded capacitor without disturbing the bandwidth (ω0/Q0). The effectiveness of the proposed design is checked through PSIPCE simulation. Monte Carlo, sensitivity, and noise analysis are also performed to ensure the robustness of the proposed design

Electronically Tunable SIMO type Mixed-mode Biquadratic Filter using Single FTFNTA

In this manuscript, a new electronically tunable single input multiple output (SIMO) type mixed-mode biquad filter is proposed. It comprises of single Four Terminal Floating Nullor Transconductance Amplifier (FTFNTA) as an Active Building Block, one resistor, and two grounded capacitors. The proposed design can generate current mode (low-pass, high-pass, and band-pass) filters and transimpedance mode (band-pass and inverting low-pass) filters simultaneously for current as an input. Similarly, for voltage as input, it can generate voltage mode (high-pass and inverting band-pass) filters and transadmitance mode (inverting band-pass and inverting high-pass) filters simultaneously. The pole frequency (ω0) and quality factor (Q0) can be tuned electronically as well as through a grounded capacitor without disturbing the bandwidth (ω0/Q0). Design is independent from the input as well as passive component matching constraint. The presence of grounded capacitors makes the circuit feasible for IC realization. The functionality of the proposed design is validated through PSIPCE simulation. To check the robustness of the proposed design Monte Carlo, sensitivity, and noise analysis is also performed