Feedforward charge injection technique in a continuous time delta-sigma modulator

In this paper, we analyze the feedforward charge injection technique (FCIT) in a continuous time delta-sigma modulator (CTDSM) and explain the theory behind improvement of SNR. We find that the feedforward charge injection technique (FCIT) in a CTDSM significantly reduces the node voltage swing at the input of the operational transconductance amplifier (OTA) and thereby relaxes the design constraint on OTA by suppressing third harmonics and thus reduces power consumption significantly. We also observe that there exist three different regions of design with respect to the power consumption out of which only one region is critical with respect to power reduction and robust design. Combined with the regions of design FCIT enables to design robust CTDSM with low power consumption.