Note on two integrator loop OTA-C configurations

A two integrator loop structure with six operational transconductance amplifiers (OTAs) and two capacitors has been proposed by Sanchez-Sinencio, et al. (1988). However, the filter functions which can be provided by this general architecture have not been available to date, although its special four OTA and two OTA derivatives have been studied. It is demonstrated that this circuit, with voltages applied to the input terminals of the OTAs inside the loops and output voltages from the circuit nodes inside the loops, offers many very useful and interesting functions such as LP, BP, HP, BS, LPN, HPN and AP without using floating capacitors, coefficient difference nulling and additional OTAs. Other existing two integrator loop structures cannot offer all the functions under similar conditions