Abstract
The realization of some new selective filters using single current differencing buffered amplifier (CDBA) and few RC components is presented. The same topology provides lowpass (LP), bandpass (BP) and highpass (HP) characteristics with appropriate choice and location of the RC components in the circuit. Incorporation of a suitable feedback loop through a voltage buffer unity-gain cell yields a tunable sinusoid oscillator. Effects of the device port mismatch errors (ε) and parasitic z-node capacitance (Cz) of the CDBA element are shown to be insignificant and corresponding sensitivities are extremely low. Satisfactory experimental verifications of the filter quality (Q) and oscillator tuning range (500 KHz ≤ fo ≤ 5 MHz) are carried out.
Highlights
The current differencing buffered amplifier (CDBA) element, introduced in the recent past as a versatile active building block [1], is being widely used for various analog signal processing/conditioning and wave generation applications [1,2,3,4,5,6,7,8,9,10]
The CDBA offers accurate unity port-transfer ratios when it is being configured by a pair of readily available current feedback amplifier (CFA-AD844 or OPA-2607 dual pack) device [4,7,8]; recently some improved models of CFA (OPA695) are being made available with bandwidth (BW) of 1.4 GHz and slew-rate of 2.5 KV/μs [11]
Function circuits based on the CDBA are cascadable owing to the availability of output nodes both in voltage source and current source modes
Summary
The CDBA element, introduced in the recent past as a versatile active building block [1], is being widely used for various analog signal processing/conditioning and wave generation applications [1,2,3,4,5,6,7,8,9,10]. Its accurate port tracking characteristics leads to extremely low circuit sensitivity [3,4,5,6] Another advantage of this active element is that its input p- and n-nodes are internally grounded such that the input-parasitic components are effectively at zero potential without introducing any nonideality [7]. The sinusoid oscillator realization could be implemented after closing the input to output feedback loop through a unity gain [12] voltage buffer (LM 6118/LM 6218). All these functions have been experimentally verified with PSPICE simulation and hardware circuit test and satisfactory results are obtained
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