Design of versatile modulator using CDTAs

In this paper, a versatile modulator circuit that can be used for amplitude modulation, frequency modulation, delta modulation and sigma delta modulation has been proposed. The circuit has been implemented with the help of CDTA blocks, grounded capacitor and resistors. The circuit basically consists of an integrator, a Schmitt trigger and an inherent clock which is used as a carrier signal thereby obviating the need for an external clock. Due to its compact size, it is suitable for IC realisation. The performance comparison of different modulation modes is made in terms of power dissipation, signal to noise ratio (SNR) and output noise voltage.