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

One input voltage and three output voltage universal biquad filters with orthogonal tune of frequency and bandwidth

This research paper contributes the one input three output voltage mode universal biquad filters with linear and electronic control of the natural frequency (w0), using two commercially available ICs, LT1228s as active device with two grounded capacitors, five resistors. The presented universal biquad filters can simultaneously provide three voltage-mode filtering functions, low-pass (LP), high-pass (HP) and band-pass (BP) without changing the circuit architecture. Furthermore, the first presented biquad filter provides low impedance at HP, BP voltage output nodes and LP, BP output voltage nodes are low impedance for the second proposed filter which is easy cascade ability with other voltage mode circuits without the employment of buffer circuits. The quality factor (Q) of both proposed filters is orthogonally adjusted from the passband voltage gain and w0. The proposed filters are simulated and experimented with commercially accessible ICs, LT1228. The simulated and experimental results demonstrate the filtering performances

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