A Simple and Economic PWM and EA Modulator Circuit Based on Modified Source-Couple Oscillator

In this article, a simple and economic pulse width modulator (PWM) and sigma delta modulator (SigmaDelta) circuit which is based on the modified CMOS source couple voltage-control oscillator is presented. The circuit can work either as PWM or SigmaDelta modulator, depending on the condition of the two bias currents which are forced of the source couples. Namely, the circuit is a PWM when these two bias currents are out of phase. Otherwise, it is a SigmaDelta modulator when both bias currents are identical. In addition, another feature of the proposed circuit is that the modulated signal can be either in voltage or current format. Moreover, the proposed circuit provides wide range of frequency operation because of few numbers of CMOS in the circuit. Furthermore, the circuit is very suitable for realization in integrated circuits (ICs) form and can be employed for optical communication application. The simulation results of the circuit are demonstrated and agreed well with theoretical anticipation