Stability Improvements in a Rail-to-Rail Input/Output, Constant Gm Operational Amplifier, at 0.4 V Operation, Using the Low-Voltage DTMOS Technique

  • Joana Correia
  • Nuno Mancelos
  • João Goes
Part of the IFIP Advances in Information and Communication Technology book series (IFIPAICT, volume 423)


The use of the dynamic threshold MOS (DTMOS) technique is evaluated in a two-stage rail-to-rail Input/Output, constant G m amplifier. The proper choice of specific transistors in which the technique should be used is presented, as well as the resulting improvements, mainly regarding stability of the circuit at low voltage operation. The DTMOS technique is used in the NMOS transistors of the folded-cascode input stage, allowing the circuit to be stable at V DD = 0.4 V, with equivalent gain and gain-and-bandwidth product (GBW) values achieved with the same V DD value, for the initial circuit operating at 0.8 V. The implemented changes allow the circuit to be stable at low voltage operations without requiring any increase in the cascoded-Miller compensation capacitors, saving circuit area and, consequently, cost.


Low-voltage DTMOS technique Low supply voltage OPAMP Low-voltage OPAMP stability issues 


  1. 1.
    Citakovic, J., Riis Nielsen, I., Hammel Nielsen, J., Asbeck, P., Andreani, P.: A 0.8V, 7μA, Rail-to-Rail Input/Output, Constant Gm Operational Amplifier in Standard Digital 0.18μm CMOS. In: IEEE Xplore, Denmark, pp. 54–57 (2005)Google Scholar
  2. 2.
    Chatterjee, S., Pun, K.P., Stanić, N., Tsividis, Y., Kinget, P.: Analog Circuit Design Techniques at 0.5V. Springer (2007)Google Scholar
  3. 3.
    Bicocchi, N., Fontana, D., Mamei, M., Zambonelli, F.: Collective Awareness and Action in Urban Superorganisms, Italy (2013)Google Scholar
  4. 4.
    Abdollahvand, S., Gomes, A., Rodrigues, D., Januário, F., Goes, J.: Design of Robust CMOS Amplifiers Combining Advanced Low-Voltage and Feedback Techniques. In: Camarinha-Matos, L.M., Shahamatnia, E., Nunes, G. (eds.) DoCEIS 2012. IFIP AICT, vol. 372, pp. 421–428. Springer, Heidelberg (2012)CrossRefGoogle Scholar
  5. 5.
    Abdollahvand, S., Santos-Tavares, R., Goes, J.: A Low-Voltage CMOS Buffer for RF Applications Based on a Fully-Differential Voltage-Combiner. In: Camarinha-Matos, L.M., Tomic, S., Graça, P. (eds.) DoCEIS 2013. IFIP AICT, vol. 394, pp. 611–618. Springer, Heidelberg (2013)CrossRefGoogle Scholar

Copyright information

© IFIP International Federation for Information Processing 2014

Authors and Affiliations

  • Joana Correia
    • 2
  • Nuno Mancelos
    • 2
  • João Goes
    • 1
    • 2
  1. 1.Centre for Technologies and Systems (CTS)UNINOVAPortugal
  2. 2.Dept. of Electrical Engineering (DEE)Universidade Nova de Lisboa (UNL)CaparicaPortugal

Personalised recommendations