Design of a Two-Stage Operational Amplifier Using Positive Feedback and Current Recycling Techniques in 180-nm CMOS Technology with Parameter Optimization via IWO

Articles in Press

Document Type : Original Article

Authors
Jalil Mazloum 1
Behzad Miryahyaei Hosseini Kerahroodi 2
Seyed M Anisheh 2
Alireza Ghorbani 2
1 Department of Electrical Engineering, Shahid Sattari Aeronautical University of Science and Technology, Tehran, Iran
2 Department of Electrical Engineering, Sar.C., Islamic Azad University, Sari, Iran
10.22034/jcse.2026.599384.1094
Abstract
The increasing use of operational amplifiers (Op-Amps) in integrated circuits has created a growing need for novel circuit structures with improved performance. Achieving high voltage gain, high speed, and adequate stability simultaneously remains one of the major challenges in operational amplifier design. In this paper, a novel two-stage operational amplifier is proposed in which a positive feedback technique is employed to enhance the voltage gain. In addition, the use of a current recycling technique improves the voltage gain and slew rate of the circuit. To achieve maximum gain while maintaining a stable phase margin, the circuit parameters are optimized using the Invasive Weed Optimization (IWO) algorithm. The proposed circuit is designed and simulated in a 180-nm CMOS technology with a 1.8-V supply voltage. The performance of the proposed structure is compared with that of a conventional two-stage operational amplifier. Simulation results are obtained using Cadence software. Furthermore, to evaluate the robustness and stability of the proposed design under different operating conditions, simulations are performed across various process and temperature corners. The obtained results demonstrate improved performance characteristics of the proposed operational amplifier compared with the conventional structure.
Keywords
Two-Stage Operational Amplifier
Positive Feedback
Current Recycling
Invasive Weed Optimization (IWO)
180-nm CMOS Technology
The CSI Journal on Computer Science and Engineering

Articles in Press, Accepted Manuscript
Available Online from 19 September 2026