This paper introduces a way to realize high-pass, band-stop and all-pass transfer functions using two-integrator loop structure consisting of loss-less and lossy integrators. The basic circuit configuration is constructed with five Operational Transconductance Amplifiers (OTAs) and two grounded capacitors. It is shown that the circuit can realize their circuit transfer functions by choosing the input terminals, and that the circuit parameters can also be independently set by the transconductance gains with the proportional block. Although the basic circuit configuration has been known, it seems that the feature for realizing the high-pass, the band-stop and the all-pass transfer functions makes the structure more attractive and useful. An example is given together with simulated results by PSPICE.

This paper introduces current-mode biquad using multiple current output operational transconductance amplifiers (OTAs) and grounded capacitors. The circuit configuration is obtained from a second-order integrator loop structure with loss-less and lossy integrators. The proposed circuit can realize low-pass, band-pass, high-pass, band-stop and all-pass transfer functions by suitably choosing the input and output terminals. And the circuit characteristics can be electronically tuned through adjusting the transconductance gains of OTAs. It is also made clear that the proposed circuit has very low sensitivities with respect to the circuit active and passive elements. An example is given together with simulated results by PSpice.