Two low-voltage high-speed CMOS frequency-insensitive PWM signal generators based on relaxation oscillator

In this paper, two new simple PWM (Pulse Width Modulation) signal generators based on a modified CMOS relaxation oscillator are introduced. Translinear current dividers are proposed to improve the circuit performance such that it is frequency insensitive to the magnitude of an input signal. In addition, the precise PWM signal can be easily achieved under low voltage consumption and the output frequency can be ranged up to several megahertz. Furthermore, both voltage and current modulating signals can be applied. Based on the features and the simplicity of the circuits, it is very suitable for developing into Integrated Circuit (IC) form in communication applications. The simulation results through PSPICE show a good agreement with theoretical anticipation.