Low-voltage high-gain large-capacitive-load amplifiers in 90-nm CMOS technology

Low-voltage and low-power multistage operational transconductance amplifiers with new and efficient gain boosting and frequency compensation schemes are proposed in this paper. The presented amplifiers are designed to drive large capacitive loads with small power consumption at low-voltage supplies. The compensation schemes exploit a single Miller capacitor and an active feedback to form the main negative feedback loops for pole splitting and two feedforward paths. The new gain boosting technique discussed here improves the dc gain with negligible effect on the frequency response. The analysis and design procedures are discussed and the performance enhancements of the amplifiers are verified. The proposed OTAs have been implemented in a standard 90-nm CMOS process and the post-layout simulation results are reported. The amplifiers consume 8.7 μW and 8.1 μW at 0.5-V supplies and achieve 12.65 MHz and 2 MHz gain-bandwidth products while driving 150-pF and 15-nF capacitive loads, respectively.