High Input Impedance Voltage-Mode Biquad Filter Using VD-DIBAs

This paper deals with a single-input multiple-output biquadratic filter providing three functions (low-pass, high-pass and band-pass) based on voltage differencing differential input buffered amplifier (VD-DIBA). The quality factor and pole frequency can be electronically tuned via the bias current. The proposed circuit uses two VD-DIBAs and two grounded capacitors without any external resistors, which is suitable to further develop into an integrated circuit. Moreover, the circuit possesses high input impedance, providing easy voltage-mode cascading. It is shown that the filter structure can be easily extended to multi-input filter without any additional components, providing also all-pass and band-reject properties. The PSPICE simulation and experimental results are included, verifying the key characteristics of the proposed filter. The given results agree well with the theoretical presumptions

A Novel Design of Low-Voltage VDIBA and Filter Application

In this study, a low-voltage low-power design of previously introduced analog signal processing element called as Voltage Differencing Inverting Buffered Amplifier (VDIBA) is presented. Level shifter current mirrors are used in the circuit design in order to accomplish the low-voltage low-power operation. The configuration operates only with ±0.4 V supply voltages and consumes power 569 μW at the bias current 50 μA. Also, low-voltage transconductor which has highly linear gm is executed with the use of bulk-driven quasi-floating gate (BD-QFG) and source degeneration techniques. The simulations of the introduced circuit have been performed with 0.18 μm TSMC CMOS technology by SPICE. The theoretical approaches have been confirmed by the simulation results

Dual-mode multifunction filter realized with a single voltage differencing gain amplifier (VDGA)

This article presents the dual-mode multifunction biquad filter realized employing only a single voltage differencing gain amplifier (VDGA), one resistor and three capacitors. The proposed filterwith one input and three outputs can configure as voltage-mode or current-mode filter circuit with the appropriate input injection choice. It can also synthesis the three standard filter functions, which are highpass, bandpass, and lowpass responses without modifying the circuit configuration. Orthogonal adjustment between the natural angular frequency (o) and the quality factor (Q) of the filter is achieved. Detail analysis of non-ideal VDGA effects and circuit component sensitivity are included. The circuit principle is verified by means of simulation results with TSMC 0.35-m CMOS process parameters

Practical realization of electronically adjustable universal filter using commercially available IC-based VBDA

This paper describes the practical realization of electronically adjustable voltage-mode universal filter with three inputs and single output (TISO) using the commercially available integrated circuit (IC)-based voltage differencing buffered amplifiers (VDBAs). The realization is resistor-less and contains only two VDBAs and two capacitors. The described filter structure can realize all the five standard biquadratic filter functions from the same configuration without needing any component matching criterions. It also exhibits low-output impedance, which enables for easy cascading in voltage-mode operation. Owing to practical VDBA realization, the filter circuit can be easily made electronically tunable with orthogonal o-Q tuning. The effects of the VDBA non-idealities on the filter performance have been analyzed in detail. To prove the theoretical finding, the performance of the studied circuit was also experimentally measured using the operational transconductance amplifie

Fractional-Order Asymptotical Phase Shifter With Flat Magnitude Response

This work deals with design of fractional-order asymptotical phase shifter having constant magnitude response within almost three decades (100 Hz – 100 kHz) and frequency dependent phase difference going from 0 to 45 degrees. PSpice simulations employing macromodels of off-the-shelf active parts brought the results suitable for brief analysis of the complete solution of our phase shifter in both frequency and time domain. Magnitude flatness with only ±0.3 dB variation and maximal phase error in the middle of operational bandwidth 3.7 degrees prove very good performance of designed circuit