A new family of CMOS inverter-based OTAs for biomedical and healthcare applications

Ricardo Póvoa, António Canelas, Ricardo Martins, Nuno Horta, Nuno Lourenço, João Goes

Research output: Contribution to journalConference articlepeer-review

5 Citations (Scopus)


This paper presents a new family of innovative operational transconductance amplifier (OTA) topologies based on CMOS inverter structures, with improved gain and energy-efficiency. This new family of OTA designs is suitable for biomedical and healthcare circuits and systems, due to the high energy-efficiency, improved gain and low level of noise contribution, when compared to the state-of-the-art in this field. In this paper, two fully-differential implementations are presented, a first one with a double CMOS branch biased by two pairs of voltage-combiners structures in both NMOS and PMOS configurations, and a second one with folded voltage-combiners specifically targeting low voltage applications, e.g., supplies below 1 V. The usage of voltage-combiners to bias the OTAs improves the gain and the gain-bandwidth product, therefore improving the energy-efficiency figure-of-merit. High values of figure-of-merit are achieved in both implementations, i.e., more than 1600 MHz × pF/mA and 2000 MHz × pF/mA, gain values above 53 dB and 50 dB under supply sources of 2 V and 0.7 V respectively. The folded voltage-combiners biased OTA is able to operate correctly under a voltage supply down to 0.7 V with proper DC biasing. The results are finally compared with state-of-the-art in this field and the potential of the circuits is fulfilled using a state-of-the-art layout-aware integrated-circuit optimization framework, AIDA, particularly relevant in order to overcome the device stacking problematic for lower voltages.

Original languageEnglish
Pages (from-to)38-48
Number of pages11
Publication statusPublished - 1 Mar 2020
Event16th International Conference on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design (SMACD) / Conference on PhD Research in Microelectronics and Electronics (PRIME) - Lausanne, Switzerland
Duration: 15 Jul 201918 Jul 2019


  • Amplifiers
  • Biomedical
  • CMOS
  • Energy-efficiency
  • Folded
  • Healthcare
  • Inverter-based
  • Low-noise
  • Low-power
  • Low-voltage
  • OTA
  • Telescopic
  • Voltage-combiners


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