On the realization of OTA-C oscillators

In this study, six tunable sinusoidal oscillator topologies, two of them known from the literature, are proposed using only CMOS operational transconductance amplifiers (OTAs) and grounded capacitors. The oscillator configurations have the properties of oscillation frequency control using the transconductance gain without affecting the oscillation condition, the suitability for very large scale integration (VLSI) since they are composed of only OTAs and grounded capacitors, and the capability of operation at high frequency. For the proposed topologies, the non-ideality effects of an OTA such as finite output conductance, and finite bandwidth are investigated, and for one of the proposed OTA-C oscillator circuits the maximum output signal level is determined using a simple formula that does not cause clipping and the slew-rate-limiting problem. The theoretical results are verified by SPICE simulation results. The oscillator topologies are simulated with the SPICE computer program and the resulting output voltage waveforms plotted.