Single-Stage Amplifier Biased by Voltage Combiners with Gain and Energy-Efficiency Enhancement

Ricardo Povoa, Nuno Lourenço, Ricardo Martins, António Canelas, Nuno Cavaco Gomes Horta, João Goes

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


This brief presents the design of a single-stage amplifier with enhanced gain and speed, without the need for using any cascode devices, positive feedback, or feed forward technique. Instead, two voltage-combiners replace the traditional tail current source, commonly employed to bias the differential pair. The resultant topology shows both additional dc gain and a gain bandwidth product enhancement. Simulation results of a properly optimized circuit, using AIDA-C, a state-of-The-Art multi-objective multi-constraint IC sizing and optimization tool, demonstrate that a dc gain above 47 dB and a figure-of-merit better than 960 MHz∗pF/mA, in corner conditions, can be achieved with this topology, in the UMC 130-nm technology. The circuit was fabricated and experimentally measured, showing an energy-efficiency figure-of-merit of 1023.6 MHz∗pF/mA.

Original languageEnglish
Pages (from-to)266-270
Number of pages5
JournalIEEE Transactions on Circuits and Systems II: Express Briefs
Issue number3
Publication statusPublished - 1 Mar 2018


  • design automation
  • energy-efficiency
  • gain enhancement
  • OTA
  • single-stage
  • Voltage-combiners


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