A current-/voltage-controlled four-slope operation square-/triangular-wave generator and a dual-mode pulse width modulation signal generator employing current-feedback operational amplifiers

This paper presents a current-feedback operational amplifier (CFOA)-based current-/voltage-controlled four-slope operation square-/triangular-wave generator. The proposed circuit can adjust the duty cycle of the output waveforms in a current- or voltage-controlled manner, and an external resistor is used to independently control its oscillation frequency. In addition, the DC level of the triangular wave can be adjusted by tuning an input voltage source. This paper also presents a CFOA-based dual-mode pulse width modulation (PWM) signal generator derived from the proposed square-/triangular-wave generator. The literature review in this paper includes previous designs, circuit operations, and the non-ideal effects and design considerations of the proposed circuits. Prototype circuits built with commercially available CFOA integrated circuits (ICs) (AD844ANs) and discrete passive components were used to execute experimental tests to verify the feasibility of the proposed circuits. The experimental results of this study are in agreement with the theoretical analysis.