Research and Design of CMOS Fully Differential Telescopic Operational Amplifier with Common Mode Feedback
In the medium or low frequency cases, the performance such as the gain or bandwidth of the fully differential operational amplifier is not good. In this paper, a fully differential telescopic two-stage operational amplifier with two-stage common-mode feedback is designed by using TSMC 250 nm technology. The first stage operational amplifier is telescopic structure, while the second stage operational amplifier is common source structure. The inner structure of common-mode feedback is continuous-time common-mode feedback circuit, and the outer structure is switched capacitor CMFB structure. It has the advantages of high gain and good linearity. It overcomes the shortcomings of common mode feedback circuit in limiting the output swing. It can stabilize the DC operating point and improve the output swing effectively. Cadence Spectre simulation results show that the common mode feedback structure keeps the common mode level at 1.25 V, the open loop gain is 67.7 dB, the phase margin is 45°, and the unit gain bandwidth is 150.7 MHz under the 2.5 V supply voltage.
KeywordsCommon mode feedback Telescopic type structure Operational amplifier
This work was supported by the Natural Science Foundation of China (No.61361011), the Natural Science Foundation of Guangxi (No. 2017GXNSFAA198363), the Basic Ability Enhancement Program for Young and Middle-aged Teachers of Guangxi.
- 6.Centurelli, F., Monsurrò, P.: A fully-differential class-AB OTA with CMRR improved by local feedback. In: European Conference on Circuit Theory and Design, pp. 1–4. IEEE (2017)Google Scholar
- 7.Wang, J., Bu, S.: An efficient frequency compensation scheme for CMFB loop in fully differential amplifiers. In: IEEE International Conference on Electron Devices and Solid-State Circuits, pp. 415–418. IEEE (2015)Google Scholar
- 8.Rahim, S.A.E.A., Azmi, I.M.: A CMOS single stage fully differential folded cascode amplifier employing gain boosting technique. In: International Symposium on Integrated Circuits, pp. 234–237. IEEE (2011)Google Scholar
- 9.Uhrmann, H., Zimmermann, H.: A fully differential operational amplifier for a low-pass filter in a DVB-H receiver. In: Mixed Design of Integrated Circuits & Systems, pp. 197–200. IEEE (2009)Google Scholar
- 10.Meysam, A.: High gain and high CMRR two-stage folded cascode OTA with nested miller compensation. J. Circ. Syst. Comput. 24(04) (2015)Google Scholar
- 11.Arbet, D., Kovac, M.: High dynamic range and low distortion fully differential difference amplifier in CMOS. In: Radioelektronika, pp. 114–117. IEEE (2015)Google Scholar
- 12.Harb, A.: A rail-to-rail full clock fully differential rectifier and sample-and-hold amplifier. In: IEEE International Symposium on Circuits and Systems, pp. 1571–1574. IEEE (2010)Google Scholar
- 13.Mahmoud, S.A.: Low voltage fully differential CMOS current feedback operational amplifier. In: Circuits and Systems 2004, vol. 1, pp. 49–52. IEEE (2004)Google Scholar
- 14.Nerurkar, S.B., Abed, K.H.: CMOS fully differential operational transconductance amplifier design for delta-sigma modulators. In: Southeastcon, pp. 52–57. IEEE (2008)Google Scholar