Electronically controlled square/triangular wave generator with amplitude adjustability and its application in light intensity measurement using commercial-off-the-shelf current feedback amplifiers

This study presents a square and triangular waveform generator using two commercial-off-the-shelf current feedback amplifiers with DC gain control, LT1228. The frequency of the square and triangular waveforms can be electronically and independently adjusted with the bias current. With this advantage feature, the proposed generator can be easily modified to generate a sawtooth waveform and electronically adjust the duty cycle of square waves. Additionally, PWM signals can also be generated from the proposed circuit. The amplitude of both square and triangular waveforms is adjustable without affecting the frequency, and the output nodes have low impedance. The circuit's performance is validated through practical implementation and testing, showing excellent agreement with theoretical analysis. The measured linear and electronic adjustment of frequency spanned from 4.83 kHz to 436.2 kHz. Furthermore, the circuit can be applied as a low-cost light intensity detection sensor.