A folded cascode OTA using current-mode gain-boost amplifier

In this report, an OTA which is used in fully differential pipelined ADC was described. Using gain-boost architecture with current-mode single-ended amplifier, this OTA reduce parasitic taking by gain-boost amplifier to achieve high-gain and high-speed. Besides, a dual phase SC-CMFB circuit is introduced, and some methods are concerned to improve the performance. Then, by optimization the layout design, OTA´s mismatch was reduced. This design was using SMIC 0.35um CMOS process and simulation both schematic and layout in Cadence. The result of the simulation shows that the OTA has a gain up to 105dB, a unity gain bandwidth of about 937MHz for a 2pF load, a settling time of about 4.4ns, a Common-Mode Range is 0.6V~3.3V, a output swing is 0.6V~3.1V, with the power supply of 3.3V, the dissipation is 39mW. This amplifier was used in a 10bit 100MHz pipelined ADC.