Temperature-Insensitive and Electronically Adjustable Square/Triangular Wave Generation based on Schmitt Trigger Oscillator

* Department of Teacher Training in Electrical Engineering, King Mongkut’s Institute of Technology North Bangkok. ** Department of Telecommunication Engineering, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang. Abstract This paper proposes 2 schemes of temperatureinsensitive square/triangular wave generator. The first scheme consists of merely an op-amp, 2 OTAs and single of resistor and capacitor. The second scheme is composed of 3 OTAs, 2 resistors and a capacitor. Their oscillation frequency is independent of both power supply level and ambient temperature. By the proposed schemes, they are simpler than the existing methods and the oscillation frequency including DC offset can be electronically tuned with wide operating frequency range. Especially, the amplitudes of output signal can be electronically adjusted in the second scheme. Another advantage is that the proposed circuits are suitable for IC implementation. The experimental results are given, they show good agreement with the theoretical anticipation.