A Constant Gm CMOS Op-Amp with Rail-to-Rail input/output stage
A Constant-gm CMOS op-amp with Rail-to-Rail input and output stage is proposed in this paper. It is based on a novel configuration that consists of four MOSFETS as dummy differential pairs to select different differential pair as input pair, according to the different common-mode voltage. The constant gm is accomplished by avoiding the input NMOS and PMOS differential pairs operating synchronously, if they operate at the same time, the tail current will be halved. The gate of the dummy differential pairs is controlled by a fixed dc voltage Vb-The resulting gm is constant within 4.65％. In addition, a class-AB output stage is employed to obtain a wide output range. The scheme can work properly for 1.5V-3.3V or 2.5V-5.5V depended on the process selected The Op Amp performs 106.6-dB dc gain, 13.85-MHz bandwidth (PM=63.86°) at 10pF//10KT2 output load and 5V power supply.
Guo-Ding Dai Peng Huang Ling Yang Bo Wang
Institute of Electronic CAD, Xidian University, Xian Shaanxi 710071,China
国际会议
上海
英文
123-125
2010-11-01（万方平台首次上网日期，不代表论文的发表时间）