Continuously controlled and discrete-level charge pumping techniques implemented in SC integrators
This paper presents two methods to reduce power consumption of switched capacitor (SC) integrators in sigma-delta analog to digital converters. The proposed two methods are based on the passive charge re-distribution technique, injecting charge into the output of the first integrator. The injected charge can be attained by a continuous function of the input voltage and feedback, or by quantizing the injected charge into three levels. In both cases, the main purpose is to minimize the initial transient voltage at the input of the first operational transconductance amplifiers (OTA), in order to bypass the slewing region of the OTA and enter into the linear settling region. Then a minor charge is left, and needs to be moved by the OTA. Using these two charge pumping techniques separately, a 10-bit performance of a conventional second-order delayed cascaded 1-bit sigma-delta modulator which consists of two SC integrators can be obtained by only consuming 60% power dissipation of the traditional structure without proposed techniques.