A novel switched-OTA utilizing slew-rate boosting for Sigma-Delta modulators

A novel switched-operational transconductance amplifier (OTA) with a wide gain bandwidth product (GBW) and a high slew-rate (SR) used in discrete-time (DT) Sigma-Delta modulator is proposed in this paper. The OTA utilizes techniques of current-starvation, resistors compensation and SR boosting to enlarge DC gain, GBW and SR remarkably, and thus speeding up its settling time with low power consumption. Using Global Foundries 0.18μm BCD 1P4M process, the switched-OTA has been implemented and the simulation results show that a DC gain of 66.8dB, a GBW of 49.3MHz and a SR of 25.4V/μs are achieved with a supply voltage of 3.3V and a load capacitor of 4.2pF. The total power consumption is about 0.68mW, and the FOM value is 996.6MHzpF/mA, which is better than other state-of-the-art works.