Skip to main content
SpringerLink
Log in

A high-constant gm rail-to-rail operational amplifier using bump-smoothing technique with stabilized output stage

  • Published:
Analog Integrated Circuits and Signal Processing Aims and scope Submit manuscript

Abstract

In this paper, a constant-gm rail-to-rail operational amplifier is proposed. The transconductance variation due to the changes in the input common-mode voltage is reduced by controlling the tail-current of the parallel nMOS and pMOS input differential pairs. In addition, a bump-smoothing technique is applied to the circuit to decline sub-threshold effects in transition regions, and therefore lower the overall gm variations. Furthermore, a stabilizing technique is employed in the output stage to minimize the fluctuation of the DC-gain and the phase margin by fixing the bias current of the cascode transistors. Thanks to stabilizing the DC-gain of the amplifier in the entire range of the input common-mode voltage, the circuit can be used as an accurate small-signal voltage amplifier in an external feedback loop for input signals with various common-mode voltages. The circuit is simulated in a standard 0.18 μm CMOS technology. The simulation results manifest that the gm variation is around ± 0.85% and the variations of the Gain–Bandwidth, the low-frequency voltage gain (DC-gain), and the phase margin are ± 1.20%, ± 3.75%, and ± 3.00%, respectively. The presented operational amplifier with the low-frequency voltage gain of 81.3 dB and the Gain–Bandwidth of 50.9 MHz for a 5-pF capacitive load consumes 1.48 mW with a 1.8 V supply voltage at the room temperature and in the typical condition.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11

Similar content being viewed by others

References

  1. RÁmirez-Angulo, J., Balasubramanian, S., LÓpez-Martin, A. J., & Carvajal, R. G. (2008). Low voltage differential input stage with improved CMRR and true rail-to-rail common mode input range. IEEE Transactions on Circuits and Systems II: Express Briefs,55, 1229–1233.

    Article  Google Scholar 

  2. Veldandi, H., & Shaik, R. A. (2018). Low-voltage PVT-insensitive bulk-driven OTA with enhanced DC gain in 65-nm CMOS process. AEU-International Journal of Electronics and Communications,90, 88–96.

    Article  Google Scholar 

  3. Song, T., Hu, J., Li, X., & Yan, S. (2007). A constant-gm constant-slew-rate rail-to-rail input stage with static feedback and dynamic current steering for VLSI cell libraries. IEEE Transactions on Circuits and Systems II: Express Briefs,54, 76–80.

    Article  Google Scholar 

  4. Hogervorst, R., Wiegerink, R. J., De Jong, P. A. L., Fonderie, J., Wassenaar, R. F., & Huijsing, J. H. (1994). CMOS low-voltage operational amplifiers with constant-gm rail-to-rail input stage. Analog Integrated Circuits and Signal Processing,5, 135–146.

    Article  Google Scholar 

  5. Lee, B., & Higman, T. (2013). 1.2 V constant-gm rail-to-rail CMOS op-amp input stage with new overlapped transition regions technique for ECG amplifier. In 2013 35th annual international conference of the IEEE engineering in medicine and biology society (EMBC), Japan (pp. 3451–3454).

  6. Chu, C., & Wang, Y. (2014). A PVT-independent constant-gm bias technique based on analog computation. IEEE Transactions on Circuits and Systems II: Express Briefs,61, 768–772.

    Article  Google Scholar 

  7. Ferri, G., Sansen, W., & Peluso, V. (1998). A low-voltage fully differential constant-gm rail-to-rail CMOS operational amplifier. Analog Integrated Circuits and Signal Processing,16, 5–15.

    Article  Google Scholar 

  8. Ramirez-Angulo, J., Sawant, M.-S., Thoutam, S., Lopez-Martin, A. J., & Carvajal, R. G. (2006). New low-voltage class AB/AB CMOS op amp with rail-to-rail input/output swing. IEEE Transactions on Circuits and Systems II: Express Briefs,53, 289–293.

    Article  Google Scholar 

  9. Dai, S., Cao, X., Yi, T., Hubbard, A. E., & Hong, Z. (2013). 1-V low-power programmable rail-to-rail operational amplifier with improved transconductance feedback technique. IEEE Transactions on Very Large Scale Integration (VLSI) Systems,21, 1928–1935.

    Article  Google Scholar 

  10. Lee, E. K. F. (2012). A sub-0.5 V, 1.5 µW rail-to-rail constant gm opamp and its filter application. In 2012 IEEE international symposium on circuits and systems, Seoul, South Korea (pp. 197–200).

  11. Carrillo, J. M., Duque-Carrillo, J. F., Torelli, G., & Ausin, J. L. (2003). Constant-gm constant-slew-rate high-bandwidth low-voltage rail-to-rail CMOS input stage for VLSI cell libraries. IEEE Journal of Solid-State Circuits,38, 1364–1372.

    Article  Google Scholar 

  12. Azcona, C., Calvo, B., Celma, S., Medrano, N., & Martínez, P. A. (2013). Low-voltage low-power CMOS rail-to-rail voltage-to-current converters. IEEE Transactions on Circuits and Systems I: Regular Papers,60, 2333–2342.

    Article  MathSciNet  Google Scholar 

  13. Hwang, C., Motamed, A., & Ismail, M. (1995). Universal constant-gm input-stage architectures for low-voltage op amps. IEEE Transactions on Circuits and Systems I: Fundamental Theory and Applications,42, 886–895.

    Article  Google Scholar 

  14. Chaturvedi, B., & Kumar, A. (2018). Electronically tunable current-mode instrumentation amplifier with high CMRR and wide bandwidth. AEU-International Journal of Electronics and Communications,92, 116–123.

    Article  Google Scholar 

  15. Razavi, B. (2016). Design of analog CMOS integrated circuits (pp. 477–479). Boston: McGraw-Hill.

    Google Scholar 

  16. Zuo, L., & Islam, S. K. (2013). Low-voltage bulk-driven operational amplifier with improved transconductance. IEEE Transactions on Circuits and Systems I: Regular Papers,60, 2084–2091.

    Article  Google Scholar 

  17. Tang, N., Hong, W., Kim, J., Yang, Y., & Heo, D. (2015). A sub-1-V bulk-driven opamp with an effective transconductance-stabilizing technique. IEEE Transactions on Circuits and Systems II: Express Briefs,62, 1018–1022.

    Article  Google Scholar 

  18. Song, T., Hu, J., Li, X., Sanchez-Sinencio, E., & Yan, S. (2008). A robust and scalable constant-gm rail-to-rail CMOS input stage with dynamic feedback for VLSI cell libraries. IEEE Transactions on Circuits and Systems I: Regular Papers,55, 804–816.

    Article  MathSciNet  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan, Iran

    Rasoul Dehghani & Ahmad Reza Danesh

Authors
  1. Rasoul Dehghani
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Ahmad Reza Danesh
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Ahmad Reza Danesh.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Dehghani, R., Danesh, A.R. A high-constant gm rail-to-rail operational amplifier using bump-smoothing technique with stabilized output stage. Analog Integr Circ Sig Process 103, 273–281 (2020). https://doi.org/10.1007/s10470-020-01620-1

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10470-020-01620-1

Keywords

Search

Navigation