【摘要】 设计了一种用于14位1.25 GS/s流水线ADC的全差分的跨导运算放大器(OTA)。采用带正反馈和增益自举电路的套筒式两级混合密勒补偿结构,并在传统密勒补偿结构基础上增加了带一组调零电阻的辅助密勒补偿结构。这两种补偿结构使得频率补偿更加灵活。对OTA的零极点进行理论分析和整体传递函数解析,再进行传递函数重构,进而实现了高增益、大带宽和高相位裕度。仿真结果表明,该OTA的增益带宽积大于17 GHz,开环增益大于94 dB。该OTA完全满足14位1.25 GS/s流水线ADC的性能要求。更多还原

【Abstract】 A kind of fully differential operational transconductance amplifier(OTA) was designed and implemented, which was used in a 14 bit 1.25 GS/s pipeline ADC. The operational transconductance amplifier adopted a telescopic two-stage hybrid Miller compensation structure with positive feedback and gain bootstrapping circuit. Based on a traditional Miller compensation structure, an auxiliary Miller compensation structure with a group of zeroing resistor was added. The two kind of compensation structures were combined to make the frequency compensation more flexible. The zero-pole and the whole transfer function of the OTA were analyzed, and the transfer function was reconstructed. Therefore, the circuit had achieved high gain, wide bandwidth and high phase margin. The simulation results showed that the gain bandwidth product of the OTA was more than 17 GHz, and the open loop gain was more than 94 dB. It had met the performance requirements of the 14 bit 1.25 GS/s pipelined ADC.更多还原